Please answer the following question: When I was a kid in Minnesota, watermelon was expensive. One of my father's friends, Bernie, was a rich businessman, who owned a large store in St. Paul. Every summer, when the first watermelons arrived, Bernie would call. Dad and I would go to Bernie's place. We' d sit on the edge of the dock , feet dangling , and got ready for a big meal. Bernie would take his knife, cut our first watermelon, hand us both a big piece and sit down next to us. Then we'd bury our faces in watermelon, eating only the heart--the reddest, juiciest, firmest, sweetest, most seed-free part--and throw away the rest. Bernie was my father's idea of a rich man. I always thought it was because he was such a successful businessman. Years later, I realized that it was not Bernie's wealth itself but his way of dealing with it that my father liked. Bernie knew how to stop working, get together with friends and eat only the heart of the watermelon. What I learned from Bernie is that being rich is a state of mind. Some of us, no matter how much money we have, will never be free enough to eat only the heart of the watermelon. If you don't take the time to dangle your feet over the dock and enjoy life's small pleasure, your work is probably hurting your life. For many years, I forgot that lesson I'd learned as a kid on the loading dock. I was too busy making all the money I could. Well, I've relearned it. I hope I have time left to enjoy the success of others and to take pleasure in the day. That's _ . I have learned again to throw the rest away. It can be learned from the passage that _ . A) one has to work hard to reach his goal B) a friend in need is a friend in deed C) watermelon is the healthiest fruit D) one should keep work-life balance
A:
D