May i get some help? Thank you! I believe it is A

Which answer choice best corrects the run-on sentence?

The boy has on a cowboy shirt it is covered in mud.

A. The boy has on a cowboy shirt, it is covered in mud.

B. The boy has on a cowboy shirt. Covered in mud.

C. The boy has on a cowboy shirt. It is covered in mud.

D. The cowboy shirt is covered in mud the boy has on.

I agree.

Technically, it's called a comma splice, but it creates the same error: two sentences jammed together incorrectly.