Recombinant DNA technology allows scientists to cut segments of DNA from one type of organism and combine them with the genes of a second organism, also called genetic engineering.
A. Recombinant DNA technology allows scientists to cut segments of DNA from one type of organism and combine them with the genes of a second organism, also called genetic engineering.
B. Allowing scientists to cut segments of DNA from one type of organism and combine them with the genes of a second organism, recombinant DNA technology is also called genetic engineering.
C. Recombinant DNA technology, also called genetic engineering, allows scientists to cut segments of DNA from one type of organism and combine them with the genes of a second organism.
D. Recombinant DNA technology, also called genetic engineering, allows scientists the cutting of segments of DNA from one type of organism and the combination of them with the genes of a second organism.
E. Recombinant DNA technology, which is also known in more familiar terminology as genetic engineering, allows scientists the opportunity to cut segments of DNA from one type of organism and combine them with the genes of a second organism.
C is the best answer.
The first concept tested in this question is modifier placement. The modifier "also called genetic engineering" should be placed as close to "Recombinant DNA technology" as possible. This eliminates option A, as it is not clear what the participle modifier "also called genetic engineering" modifies - "organism"/"technology"/"genes"?
E is unnecessarily wordy - "which is also known in more familiar terminology as genetic engineering" can be constructed more concisely as "also called genetic engineering". Eliminate
B - Now this is an interesting constructing as the phrase "Allowing scientists..." is acting as a modifier describing "Recombinant DNA technology"; ADDITIONALLY "is also called.." is acting as a verb for "RDT". However, if we remove the initial modifier from option B, the main sentence essentially becomes "recombinant DNA technology is also called genetic engineering", which is significant distortion wrt the original meaning of the question prompt. The modifier in option B should be an essential part of the main subject "RDT", and should not be a non-essential modifier offset by commas. The main intent of writing the sentence is to illustrate what "RDT" allows scientists to do - B makes it sound as if the main idea of the sentence is to give an alternate name for "RDT". Eliminate
Between C and D -
Both options have the modifier "also called GE" placed right next to "RDT", which is correct. The only difference is D uses two noun/gerund forms - "the cutting.." AND "the combination..", whereas B uses 2 verb forms : "to cut.." and "to combine...". On the GMAT, PROVIDED that both options are grammatically and logically correct, the verb form is almost always the way to go, as the noun form results in an extremely indirect/awkward/unnecessarily wordier construction. This makes option D inferior to C.
Hence C is the best answer.