Question

Which sentence does not contain any errors in comma usage?

A.
The artist paints landscapes and animals and then she sells her artwork at the outdoor market.

B.
Many farmers planted corn, and others planted soy beans.

C.
Jeremy sent a letter in the mail, but, later that week Katie replied by e-mail.

D.
A factory recently closed in Pittsburgh but, another one is opening soon.

Answer 1

Your answer is going to be B. It is a complete sentence before the comma. 

Answer 2

B. is correct because it is separating a main clause from a subordinate clause. :)