Combine the following sentences using a subordinate conjunction.
Sentence: Supper won't be ready for another half hour. We have time for a bit of ping pong.
A: Supper won't be ready for another half hour, so we have time for a bit of ping pong.
B: Since supper won't be ready for another half hour, we have time for a bit of ping pong.
C: Supper won't be ready for another half hour, we have time for a bit of ping pong.