Please HELP ME !!
Choose the sentence that is written correctly.
	A.	Jason and Ethan went to the conference, they learned a lot about the new software.
	B.	Jason and Ethan went to the conference, and they learned a lot about the new software.
	C.	Jason and Ethan went to the conference and they learned a lot about the new software.
	D.	Jason and Ethan went to the conference when they learned a lot about the new software.