A. dermestid beetles feed on the decaying flesh of animal carcasses, pulling -
Incorrect...when referring to the entire class 'the' with the class name is used. For example, we dont say 'lions are kings of the jungle' when referring to the entire class. Instead we say 'The lion is the king of the jungle' which refers to the entire group/class
B. dermestid beetles feed on the decaying flesh of animal carcasses and pull -
Same as A
C. the dermestid beetle feeds on the decaying flesh of animal carcasses and pulls -
Incorrect. It is important to understand the meaning and not just focus on the structure. Although this one looks parallel, the sentence means that it feeds by pulling.
so the present participle in option D is correct.
D. the dermestid beetle feeds on the decaying flesh of animal carcasses, pulling -
Correct
E. the dermestid beetle feeds on the decaying flesh of animal carcasses and it pulls -
Same as C

Meaning Analysis: The curators use dermestid beetles in the preparation of animal skeletons for display because these beetles feed on flesh and by doing so, they pull the fat out of the bone.

Error Analysis: Notice this phrase in the non-underlined portion of the sentence – “…with its mouthparts…”. Singular pronoun “its” does not agree in number with its plural antecedent “dermestid beetles”. Hence, this antecedent must be changed to singular.

POE:

A. dermestid beetles feed on the decaying flesh of animal carcasses, pulling: Incorrect for the reason stated above.

B. dermestid beetles feed on the decaying flesh of animal carcasses and pull: Incorrect.
1. Same pronoun antecedent number agreement error.
2. The unintentional parallelism between “feed” and “pull” now separates these two activities as independent. It fails to connect the pulling with feeding.

C. the dermestid beetle feeds on the decaying flesh of animal carcasses and pulls: Incorrect. Same parallelism error as in choice B.

D. the dermestid beetle feeds on the decaying flesh of animal carcasses, pulling: Correct.

E. the dermestid beetle feeds on the decaying flesh of animal carcasses and it pulls: Incorrect.
1. Same parallelism error as in Choice B.
2. Pronoun “it” is not needed.