Question 35 - 37 refer to following paragraph:

M: Hi, Tiffany. Do you know what happened to the company car? I tried to reserve it today, but I was told it's being repaired.
W: (35) When Mark was driving yesterday, he got a flat tire. I just heard that the car should be out of the repair shop by this evening. I'll let you know when they call me.
M: Oh, that's good news. (36) I was worried because I need it tomorrow morning to pick up an important client from the airport.
W: Ah, isn't that Mr. Lee from Beijing? (37) Just in case, why don't you call a local car rental business and reserve a car for tomorrow? If the company car is fixed in time, you can cancel.

35. What does the woman say caused the problem?