【正确答案】 C

【答案解析】[听力原文]
   One evening several years ago, on a visit to my hometown, I sat with my wife, my son, and my parents at a restaurant. After a wonderful dinner, the waiter set the bill in the middle of the table. That's when it happened: my father did not reach for it.
   Conversation continued. Finally I realized that I was supposed to pick up the bill and pay for the dinner! After hundreds of restaurant meals with my parents, after a lifetime of thinking of my father as the one who paid for our meals, it had all changed. I reached for the bill, and my view of myself was suddenly changed. I finally became an adult before my parents.
   Some people mark off their lives in years; I measure mine in small events. I did not become a young man at a particular age, like 13, but rather when a kid walked into the store where I worked and called me "mister." He repeated it several times, looking straight at me. The realization came to me all of a sudden: Me! I was suddenly a mister.
   One day I bought a house. One day I became a father, and not too long after that I picked up the check for my father. These events are milestones of my life.
   What is the passage about?