Question

3. Why ________ yesterday? a) were you late b) you were late c) you was late

Answer 1

Why were you late yesterday

Answer 2

The correct option would be:

b) you were late

The sentence "Why were you late yesterday?" is the correct grammatical form. "You" is the second-person singular pronoun, and "were" is the past tense of the verb "to be" that agrees with "you."