在句子"When I joined the Navy, he “joined” too. And when I came home on leave, he saw to it that I visited his office. Introducing me, he was really saying, “This is my son, but it is also me, and I could have done this, too, if things had been different.”" 中(have done) this指代的是___________ A. Introducing me B. visited his office C. what the son has achieved, i.e. serving in the Navy