Antarctica has a thick ice cover. It has the highest average elevation of all the continents.

Which choice shows the sentences combined with a subordinating conjunction?

A.

Antarctica has a thick ice cover, it has the highest average elevation of all the continents.
B.

Antarctica has a thick ice cover. Since it has the highest average elevation of all the continents.
C.

Antarctica has a thick ice cover, since it has the highest average elevation of all the continents.
D.

Antarctica has a thick ice cover; since it has the highest average elevation of all the continents.