He smiled hugely , proud of himself for surprising Jack . He had n't liked lying to him on the phone , but he had been thinking for a week about surprising Jack and getting home a day early , and he had to admit that he was happy about being able to fool Jack and make him think he was coming on Thursday , when in reality he was flying in the day before , on Wednesday . What he had n't counted on was getting delayed in Chicago .

Question: What may be the reason he was delayed in Chicago ?
Answer: He forgot to write down his phone number .The weather was too cold to fly safely .None of the above choices .The weather was too warm to defrost planes .