Which sentence is a run-on sentence?

AMost dogs are loyal and obedient, they are easy to train.
BBetween the two animals, which one sheds the most?
CDogs are colorblind; cats are, too.
DWould you prefer a dog or a cat as a pet?

Verified Answer :

C because it has to have a comma between color blind and cats not semicolon

CI think c because you are talking about dogs not cats always stay on one subject