Step into the shoes of a peer reviewer examining a biology manuscript. Select the correct combination of articles to complete the author's argument.

"In evolutionary biology, _____ human eye is often cited as an example of complex adaptation, though _____ vision itself evolved independently multiple times."

The correct answer is the / — (no article).

In scientific and academic writing, the definite article the is frequently used with a singular countable noun to represent an entire class, system, or species (e.g., "the human eye", "the computer").

"Vision," however, is an abstract, uncountable noun functioning in a general sense here, so it takes the zero article.