Correct option is A
The correct option is (a) "my brother to get."
This substitution correctly maintains the structure needed in the sentence by directly linking the verb "asked" with the object "my brother" and the infinitive "to get."
In this construction, "asked" does not require a preposition like "for" when directly followed by an object and an infinitive, making it concise and grammatically correct.
Grammatical rule used: When the verb "ask" is followed by an object and an infinitive, the preposition "for" is not necessary. Example: He asked me to help.