The pesticide Azocide, introduced to central valley farms

Straight and clear the answer is "E". Do you need explanation for this one? Please tell..I will try to explain

a. because other pesticides' chemical compositions already in wide use
- sounds like it is the chemical compositions that are already in wide use, rather than the other pesticides, themselves.
b. because of the chemical compositions of the pesticides already in wide use
- most appropriate. B is my choice..
c. due to other pesticides already in wide use, whose chemical compositions have been
- incorrectly allocates the reason. Azocide is ineffective not just because of other pesticides already in use, but rather because the chemical composition of those pesticides neutralizes the desired effects of Azocide.
d. since, due to the chemical compositions of other pesticides already in use, those pesticides have been
-too awkward, and wordy?
e. because of other pesticides and their chemical compositions already in use, which have been
-separates "other pesticides" and "their chemical compositions" into distinct entities.

Anand

B is in the format "X is not effective, because of Y in Z neutralizing X".

So, that still stands.

Anand

C for me.

C states that the cause is "due to the other pesticides in wide use, whose chemical compositions have been"

I think the "have been" clearly refers back to the fact that Azocide was introduced a few months ago and up to now, its desired effect has been neutralized.

B would be better if are was added at the end... "because of the chemical compositions of the pesticides already in wide use ARE neutralizing..." Without are, it sounds awkward to me.

Thanks for responses. OA is 'C'
'Due to' should be used,

I also chose B but 'because of' in B is incorrect...C it is.

There is just one more thing i want to get clarified.

Due to can only be used when it can be replaced by caused by.

Now C says:
The pesticide Azocide, introduced to central valley farms three summers ago, has proven ineffective due to other pesticides already in wide use, whose chemical compositions have been

The pesticide Azocide, introduced to central valley farms three summers ago, has proven ineffective caused by other pesticides already in wide use, whose chemical compositions have been

This is awkward.

Now because of can only be used when it can answer the question Why?

Now B says
The pesticide Azocide, introduced to central valley farms three summers ago, has proven ineffective because of the chemical compositions of the pesticides already in wide use

This answers the question why the pesticide has proven ineffective.

So B makes sense.

Source: https://www.agriculture.purdue.edu/agcomm/ontarget/0609/Grammar_trap.htm

Please see the link above....Any thoughts??