Which sentence does not contain any errors in comma usage?

A.Mr. Farnsworth whom we know from camp can play the guitar.

B.Lucy whom we haven't met, will arrive at the train station in the morning.

C.That wonderful singer, whose voice reminds me of yours will give a concert at the auditorium.

D.Mr. Stanford, whose first name is Harold, owns two gas stations in our town.

Question

Which sentence does not contain any errors in comma usage?

A.Mr. Farnsworth whom we know from camp can play the guitar.

B.Lucy whom we haven't met, will arrive at the train station in the morning.

C.That wonderful singer, whose voice reminds me of yours will give a concert at the auditorium.

D.Mr. Stanford, whose first name is Harold, owns two gas stations in our town.