Find the incorrect part of the sentence:
Neither of the two brothers are trustworthy.

Correct option is B

Option (b) contains an error.
Detailed explanation: The subject “Neither of the two brothers” is singular because neither refers to “not one and not the other” (i.e., each taken singly). Therefore, it must take a singular verb: is, not are. The correct sentence is: “Neither of the two brothers is trustworthy.”
Grammatical rule used: Indefinite determiners neither, either, each, every take singular verbs, even when followed by a plural noun phrase (e.g., neither of the answers is ).
Example: Either of the solutions is acceptable.
Information booster: While none of can take singular or plural depending on emphasis, neither of is standardly singular in formal English.