Read the sentence given below to find out if it contains any error. The error, if any, will be in one part of the sentence. If the sentence is error free, select No error or option 5. Ignore error of punctuation if any.

Palaeontologists have been puzzled at how gigantic flying (A)/ azhdarchid pterosaurs has managed to support their thin (B)/ necks as they take off and (C)/ fly while carrying heavy prey animals. (D)/ No error (E)