Question

however when under duress by pests, such as when ants destroy their roots, plants are known to produce chemicals to ward off invaders. so for this study, barbero and her colleagues grew oregano in enclosed terrariums with myrmica ants, and then collected the chemical scents emitted to produce chemicals to ward off invaders.
the researchers found that the plants made twice as much of a chemical agent called carvacrol versus normal plants grown without myrmica ants.
carvacrol is a known bug killer, but in a surprising twist, the researchers found that myrmica ants switch on a set of genes that neutralize oreganos chemical weapon. meanwhile, other types of ants lack this defense and succumb to carvacrol, the team found.
use the excerpt to answer the question.
which detail was left uncertain in the article?
(1 point)
why plants produce chemicals to ward off invaders
the definition of carvacrol
how much carvacrol the oregano plants made
why ants other than myrmicas are not resistant to carvacrol

Explanation:

• For the first option: The article states plants produce chemicals when under pest duress (like ants destroying roots) to ward off invaders, so the reason is clear.
• For the second option: The article only mentions carvacrol is a bug killer and its production by oregano, but does not define what carvacrol is.
• For the third option: The article says "the plants made twice as much of a chemical agent called carvacrol versus normal plants", so the amount (relative to normal plants) is given.
• For the fourth option: The article explains Myrmica ants have a defense (switch on genes to neutralize) and other ants lack it, but it does not address why other ants are not resistant. Wait, no—wait, the question is which detail is left uncertain. Wait, let's re - evaluate. Wait, the article says Myrmica ants can neutralize, others can't. But does it leave uncertain why others are not resistant? Wait, no, the article just states the fact. But the second option: the definition of carvacrol. The article never defines carvacrol, just says it's a bug killer and how much oregano produces. So the definition of carvacrol is left uncertain. Wait, let's check again:

1. "why plants produce chemicals to ward off invaders": The article says "when under duress by pests... plants are known to produce chemicals to ward off invaders"—so the reason (pest duress) is given. So not uncertain.

1. "the definition of carvacrol": The article only says "Carvacrol is a known bug killer"—it doesn't define what carvacrol is (chemical structure, formal definition, etc.). So this detail is uncertain.

1. "how much carvacrol the oregano plants made": The article says "twice as much... versus normal plants"—so the relative amount is given. So not uncertain.

1. "why ants other than Myrmicas are not resistant to carvacrol": The article says "other types of ants lack this defense and succumb to carvacrol"—it states the fact but doesn't explain why. Wait, but the question is which is left uncertain. Wait, but the second option: the definition of carvacrol. The article doesn't define it, so that's uncertain. The fourth option: the article doesn't explain why other ants are not resistant, but is that a detail left uncertain? Wait, the article's focus is on the study with Myrmica ants and oregano. The definition of carvacrol is not provided, so that's a detail left uncertain.

Wait, maybe I made a mistake earlier. Let's go step by step:

• Option 1: Reason for plant chemical production is given (pest duress) → not uncertain.

• Option 2: Definition of carvacrol—article only says it's a bug killer, no definition → uncertain.

• Option 3: Amount of carvacrol—"twice as much as normal plants" → amount (relative) is given → not uncertain.

• Option 4: Why other ants not resistant—article states they lack defense, but doesn't explain why. But is this a detail left uncertain? Wait, the article's main point is about the study on oregano and Myrmica ants. The definition of carvacrol is a basic detail about the chemical that is not provided. So the definition of carvacrol is left uncertain.

Wait, but let's check the options again. Wait, the fourth option: "why ants other than Myrmicas are not resistant to carvacrol"—the article says Myrmica ants have a defense, others don't. But it doesn't tell us why others are not resistant. But is that a detail left uncertain? Or is the definition of carvacrol more clearly uncertain?

Yes, the definition of carvacrol: the article never defines what carvacrol is (e.g., its chemical formula, its classification, etc.). So this detail is left uncertain.

Answer:

B. the definition of carvacrol