What is the problem with the following sentence?

I saw a cat run across the road, it was black with shining eyes.

a. There is no problem.	b. It is an incomplete sentence.
c. It needs a conjunction or a period.	d. It has a verb tense problem.

C. IT NEEDS A CONJUNCTION OR A PERIOD because it's really two complete sentences in one and you can't join two sentences with only a comma.