Question 23 is based on the passage you have just heard.

    (25) The British are supposed to be famous for laughing at themselves, but even their sense of humour has a limit, as the British retailer Gerald Ratner found out to his cost. (22) When Ratner took over his father's chain of 130 jewelry shops in 1984, he introduced a very clear company policy. He decided that his shops should sell downmarket products at the lowest possible prices. It was a great success.The British public loved his cheap gold earrings and his tasteless silver ornaments. By 1991, Ratner's company had 2,400 shops and it was worth over 680 million pounds. But in April of that year, Gerald Ratner made a big mistake. (23) At a big meeting of top British businesspeople, he showed up and explained the secret of his success. "People say 'How can we sell our goods for such a low price?' I say 'Because they are absolute rubbish.'" His audience roared with laughter. But the British newspapers and the British public were not so amused. (24) People felt insulted and stayed away from Ratner's shops. Sales fell and 6 months after his speech, Ratner's share price had fallen by 42%. The following year, things got worse and Gerald Rather was forced to resign. By the end of 1992, he lost his company, his career and his house. Even worse, 25,000 of his employees had lost their jobs. (25) It had been a very expensive joke.

(23). On what occasion did Gerald Ratner explain the secret of his success?

解析：细节理解题。题目为：Gerald Ratner在什么场合下解释了他成功的秘密？根据原文At a big meeting of top British businesspeople, he showed up and explained the secret of his success可知，在一次英国顶尖商人的大型会议中，他出席并解释了他成功的秘密。选项D与原文完全一致。