Change into Passive! George Had Repaired Many Cars Before He

Multiple Choice

Change into passive! George had repaired many cars before he received his mechanic's license.

A) many cars had been repaired by george before he received his mechanic's license.
B) before he received his mechanic's license, many cars had been being repaired by george.
C) before he was received his mechanic's license, many cars had been repaired by george.
D) many cars had been being repaired by george before he was received his mechanic's license.