Sentence Correction

The majority of scientists believe that to reduce and stabilize atmospheric concentrations of carbon dioxide, emissions must be cut at the source by fossil fuels that are burned more efficiently and, in some cases, by alternatives such as hydrogen fuel cells that can replace fossil fuels altogether.

(A) fossil fuels that are burned more efficiently and, in some cases, by alternatives such as hydrogen fuel cells that can replace fossil fuels altogether
(B) fossil fuels that are burned more efficiently and, in some cases, those that are replaced altogether with alternatives such as hydrogen fuel cells
(C) burning fossil fuels more efficiently and, in some cases, by replacing fossil fuels altogether with alternatives such as hydrogen fuel cells
(D) more efficiency in the burning of fossil fuels and, in some cases, by alternatives such as hydrogen fuel cells that can replace fossil fuels altogether
(E) the more efficient burning of fossil fuels and, in some cases, by fossil fuels that are replaced altogether with alternatives such as hydrogen fuel cells

[spoiler]OA:C[/spoiler]

Just see the meaning of the sentence (and parallelism, ), you will select C.

....emissions must be cut at the source by <X and Y> ......

X, Y should be some process, people etc.

X, Y can not be fossil fuel : eliminate A, B

E : first part is right but again second part is "by fossil fuel"

C is correct.
burning fossil fuels more efficiently
by replacing fossil fuels

both are process, and parallel

paes wrote:Just see the meaning of the sentence (and parallelism, ), you will select C.

....emissions must be cut at the source by <X and Y> ......

X, Y should be some process, people etc.

X, Y can not be fossil fuel : eliminate A, B

E : first part is right but again second part is "by fossil fuel"

C is correct.
burning fossil fuels more efficiently
by replacing fossil fuels

both are process, and parallel

I was correct in choosing the answer.

I have a confusion about the "more efficiently".
We know that "more XX that YY".

Where is the "more ...than" in the correct option, C?

Thanks.

I don't have a definite answer for your query.

But Let me try :

e.g.
Now, you can looking more intelligent.

Here meaning of the sentence itself is very clear that we are comparing to you only, with your previous stage.
So no need to write 'more than'

Anyway,
Some expert can put some more light on this query.