Derek left work early. There were still lots of projects that needed to be finished.
Which sentence correctly joins these two simple sentences into a compound sentence?
A.
Derek left work early and there were still lots of projects that needed to be finished.
B.
Because Derek left work early there were still lots of projects that needed to be finished.
C.
Derek left work early, but there were still lots of projects that needed to be finished.
D.
Derek left work early there were still lots of projects that needed to be finished.