Which one is a run-on sentence?
A.
A camel can go without water for days and days, he stores water in the hump on his back.
B.
Since the backroom was vacant, Jim used it as a studio.
C.
Because John assisted his neighbors, they were able to paint his house twice as fast.
D.
If that old, half-burned house were reconstructed, someone might buy it and move into it.