reliance on fossil fuels:

[\'manpreet singh]

There are hopeful signs that we are shifting away from our heavy reliance on fossil fuels: more than ten times as much energy is generated through wind power now than it was in 1990.

(A) generated through wind power now than it was
(B) generated through wind power now as it was
(C) generated through wind power now as was the case
(D) now generated through wind power as it was
(E) now generated through wind power than was the case
ans c

[ganeshrkamath]

There are hopeful signs that we are shifting away from our heavy reliance on fossil fuels: more than ten times as much energy is generated through wind power now than it was in 1990.

(A) generated through wind power now than it was
(B) generated through wind power now as it was
(C) generated through wind power now as was the case
(D) now generated through wind power as it was
(E) now generated through wind power than was the case
ans c

Idiom : as much ... as ...
Eliminate A and E.
In B and D, it's not clear what "it" refers to.
Choose C

[GMATGuruNY]

There are hopeful signs that we are shifting away from our heavy reliance on fossil fuels; more than ten times as much energy is generated through wind power now than it was in 1990.

A. generated through wind power now than it was
B. generated through wind power now as it was
C. generated through wind power now as was the case
D. now generated through wind power as it was
E. now generated through wind power than was the case

In A and E, as much...THAN is unidiomatic.
The correct idiom is as much X AS Y.
Eliminate A and E.

In B and D, it (subject pronoun) seems to refer to more than ten times (the preceding subject).
The result is a nonsensical comparison:
MORE THAN TEN TIMES is generated now as MORE THAN TEN TIMES was [generated] in 1990.
Eliminate B and D.

The correct answer is C.