When a student studies the way the English language has evolved, the student is studying English's

alliteration.

development.

origin.

repetition.

I believe the answer would be development because that tells how something changes and grows over time, which is the same general meaning of the world evolve.

Answer;

When a student studies the way the English language has evolved the student is studying English's Development.

Explanation;

Development represent the process of growing, changing or advancing. Thus, English's development involves the study of how English language has grown, changed or advanced with time.