The correct answer is: C. Is construction material sold by them?
The other options are incorrect because they do not use the correct verb tense. The verb “sell” is in the present tense, so the correct answer must also be in the present tense. Option A, “Does construction material sold by them?”, uses the past tense verb “sold”. Option B, “Is construction material selling by them?”, uses the present progressive verb “selling”. Option D, “Does construction material sell by them?”, uses the present tense verb “sell” but does not agree with the subject “construction material”.
The sentence “Do they sell construction material?” is asking about the present tense action of selling construction material. The correct answer, “Is construction material sold by them?”, uses the present tense verb “sell” to agree with the subject “construction material” and to indicate that the action of selling construction material is happening now.