Sentence Correction

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 is A
Can an Expert explain the parallelism om why C is correct? What makes it different from B