Concept:Use the subject pronoun "I" when the pronoun is part of the subject of the sentence.
Explanation:The sentence is: "My mum and ____ visited Joseph."
The verb is "visited", so we must ask: Who visited Joseph?
The answer is "My mum and I", meaning the blank is in the subject part of the sentence.
Subject pronouns include
I, we, you, he, she, it, and they.
Object pronouns include me, us, you, him, her, it, and them.
Since the blank is part of the subject, the subject pronoun "I" is correct.
"Me" would be used as an object, for example: "Joseph visited me."
"Myself" is a reflexive pronoun, used when the subject and object are the same, like "I hurt myself."
"Ourselves" is plural and does not fit here with "My mum and I".
Thus, the completed sentence is: "My mum and I visited Joseph."
Answer:A. I