AでもBでも適訳は1のみ。
A. 彼は蚊帳の外に置かれた。
1. He was left out of the loop.
2. He was placed outside the mosquito net.
3. He was placed outside the mosquito net.
B. 私は彼女とは馬が合います。
1. I get along well with her.
2. I am a good horse with her.
3. I have a horse with her.