Question

read the following incomplete summary of the text. which is the best sentence to add in order to create a more complete summary?

hornbills are a type of bird known for their unique bills with casques, but there are many differences found from one species of hornbill to another. malaysia’s huge rhinoceros hornbills live in rainforests and have large, colorful, upturned casques. africa’s southern yellow - billed hornbills live in savannas and hunt with mongooses.

some hornbills have become critically endangered, but efforts are currently underway to protect them.

the helmeted hornbill is the least attractive of all the many birds in the hornbill family.

southeast asia’s helmeted hornbills have leathery skin on their necks and solid red casques.

to help hold up their heavy bills and casques, hornbills’ top two neck vertebrae are fused together.

the southern yellow - billed hornbill is often hunted for its unique salt - and - pepper feathers.

Explanation:

The original summary focuses on differences between hornbill species (habitats, casques, behaviors) and then shifts to their endangerment. We need a sentence that continues describing a hornbill species' characteristics.

• Option 1: Talks about attractiveness, which is not related to the summary's focus on species differences/features. Eliminate.
• Option 2: Describes Southeast Asia’s helmeted hornbills’ physical features (leathery neck skin, red casques), which fits the pattern of detailing different hornbill species’ traits (like the previous examples of Malaysian and African hornbills).
• Option 3: Discusses a structural adaptation (neck vertebrae) rather than species - specific traits like the other examples. Eliminate.
• Option 4: Focuses on hunting for feathers, which is a threat, but the next part of the summary already moves to endangerment/protection. This would be a disjointed transition. Eliminate.

Answer:

B. Southeast Asia’s helmeted hornbills have leathery skin on their necks and solid red casques.