【正确答案】 B

【答案解析】原文：M：Excuse me. When does flight 645 leave?W：Actually, it is delayed until 15:30.Q：What do we know about the flight?问题问的是“为什么女士联系不上弗兰克先生”。通过对话内容可知,男土说弗兰克先生出差去了,故选B。