Question

if the students would of studied, they might have passed the test
incorrect verb form
parallel structure
no error
capitalization

Explanation:

The sentence "If the students would of studied, they might have passed the test" has an error in the verb phrase "would of studied". The correct form should be "had studied" (using "had" instead of "of" as part of the past conditional structure). So the error is in the verb form.

Answer:

Incorrect verb form