I believe this is a pronoun reference error. In the original sentence, it is not clear what "if" is referring to. It could either refer to "Restorers" or "the colors". I believe the answer is C, because colors can't be allowed to do anything, as they are inantimate. "If they are" makes it clear that the object being allowed to "remove and replace" is "Restorers". So, "Restorers say that if they are allowed to remove and replace" makes a clear pronoun reference.

Hope this helps.

Hi qwerty12321,

This is a classic conditional sentence with the "if clause" at the beginning. It has the following format: the "if clause" in the simple present, and the main clause containing will-future infinitive. Here is a simple example of this kind of sentence:

If I study, I will do well on the GMAT.

Answer A just contains the "if," not the noun/pronoun and verb. Without the noun/pronoun, it is unclear who is doing what.

Answer C has the correct combination to make a correct conditional sentence. Here is a simplified form of the sentence: "If they are allowed to do something, the colours will shine."

I hope this helps!

Hi,

Could someone help with this one, why could not B - "If it is" be correct answer? I mean, why could not we use "It is" in the same way as "It is easy/difficult/essential to...", in which cases "it" does not really have any antecedent?

Thanks for helping me