Question

and discovered that it was from a genus of fungus known as penicillium. he named the bacteria - killing substance emitted by this fungus penicillin and published his findings in a scientific journal.
through careful and thorough research, scientists howard florey and ernst boris chain were later able to use penicillin to develop the first antibiotics - drugs that are used to this day to fight serious infections like pneumonia. thus, although the initial discovery of penicillin occurred by accident, it was ultimately flemings determination to find a cure for bacterial infections and florey and chains assiduous labor that were responsible for the development of these life - saving drugs.
what is the meaning of assiduous as used in the passage?
fast - moving
unexpected
unrecognized
diligent

Explanation:

The passage mentions that Florey and Chain did "careful and thorough research" to develop antibiotics. The word "assiduous" should have a similar meaning to describe their hard - working nature. "Diligent" means showing care and effort in one's work, which fits the context. "Fast - moving" is about speed, "unexpected" is about surprise, and "unrecognized" is about not being known, none of which match the context of research work.

Answer:

diligent