BTGmoderatorDC wrote:The pesticide Azocide, introduced to central valley farms three summers ago, has proven ineffective because other pesticides' chemical compositions already in wide use neutralizing its desired effect.

A.because other pesticides chemical compositions already in wide use

B.because of the chemical compositions of the pesticides already in wide use

C.due to other pesticides already in wide use, whose chemical compositions have been

D.since, due to the chemical compositions of the other pesticides already in use, those pesticides have been

E. because of other pesticides and their chemical compositions already in use, which have been

because + NO OF must be followed by a CLAUSE.
A: because other pesticides...neutralizing its desired effect.
Here, the red portion after because lacks a verb and thus does not constitute a clause.
Eliminate A.

B: The pesticide Azocide has become ineffective...because of the chemical compositions
E: The pesticide Azocide has proven ineffective...because of other pesticides
In these options, the conveyed meaning is that the nouns in red have caused Azocide to be proven ineffective.
Not the intended meaning.
The intended meaning is that Azocide has proven ineffective not because of these nouns but because of an ACTION: the chemical compositions of other pesticides HAVE BEEN NEUTRALIZING THE EFFECT of Azocide.

Technically, due to is an ADJECTIVE.
For this reason, it should serve to modify a NOUN.
In C and D, it is unclear what noun is being modified by due to.
Regardless, neither C nor D clearly conveys that Azocide has proven ineffective because of the blue action discussed above.
Eliminate C and D.

None of the answer choices is viable.
I would ignore this SC.