In the 1980s advertising revenues accounted for approximately 40% of operating profits of a typical local newspaper; in the 1990s this proportion increased to 57%.

A)newspaper; in the 1990s this proportion increased to 57%.

B)newspaper; in the 1990s they increased by 57%.

C)newspaper, in the 1990s they increased to 57%.

D)newspaper; increasing to 57% in the 1990s.

E)newspaper, which increased to 57% in the 1990s.

OA A

In OA what THISrefer to?

Also please explain each options.