Which is the passive voice of: “Mr. Butt broke the antique vase”?

MCQ Quiz

8. Which is the passive voice of: “Mr. Butt broke the antique vase”?

a
The antique vase was broken by Mr. Butt as he walked through the store.
b
The antique vase is broken by Mr. Butt as he walked through the store.
c
The antique vase had been broken by Mr. Butt as he walked through the store.
d
The antique vase was broken as Mr. Butt walked through the store.