Love Apartment 2 Episode 20 Why did the old man let Ceng Xiaoxian choose D? Then why did Ceng Xiaoxian choose B in the end?

This is a passage from Slumdog Millionaire. In Poverty, the host pretended to cheat in the toilet in order to prevent the protagonist from winning the lottery, and gave the protagonist the wrong answer. Unexpectedly, the protagonist didn't want to win the prize, so he chose the answer he thought was wrong, and the result was a mistake in winning the grand prize.

In love, Xiaoxian thinks that the old man is the master. After seeing the answer left by the old man, it reminded him of the movie, so he chose B and finally won the grand prize. But then I won the grand prize, my career was successful, but I lost my friends forever. Decades later, when he was old, he saw the mirror and suddenly remembered that the person who gave himself an answer in the toilet decades ago was himself decades later. But he doesn't understand why he gave himself the wrong answer d? Recalling these decades of lonely life, he realized that from the perspective of the topic, choosing B was correct; But from the perspective of life, he chose B for wealth and success, but lost his friends and love. Although choosing D is wrong, life is really perfect and full. So for life, D is the correct answer. According to their decades of life experience, the old sage tells the young sage what the real correct answer is.