Which is a run-on sentence?

ARoses have sharp thorns, but they are beautiful just the same.
BAfrican violets usually have purple flowers some have white ones.
CAcorns drop from oak trees, and they are a food source for squirrels.
DSunflowers are usually yellow, yet some are red or orange.

Verified Answer :

Your answer would be B. A run-on sentence is a long sentence without commas or periods to divide it.

Answer:

i would think that it would be B  

Explanation:

because it does not have any commas or periods