GMAT Sentence Correction (SC) | Re: Reporting that one of their more crippling malfunctions has

We need to find the pronoun referent for its/their. That is, what noun refers to its/their. When we have a participle phrase (as we do here, beginning with 'reporting...'), the its/their must refer to the noun that comes immediately after the comma. In this case, the participle phrase is modifying the noun 'the engineering squad', which is singular.

Therefore, we wantits nottheir . Eliminate (A) and (B).

BTW: 'Maintenance systems' is a direct object and therefore is not the subject of the