^^That's not exactly true. Tasks on the critical path refer to the tasks with the least amount of slack, or better put, tasks that if not completed first will adversely affect the end date of the project. I've seen some PM's consider tasks with <5 days of slack as their determining factor, others go as high as 10 days. Either way, it wasn't a trick question, the interviewer just wanted to see if you understood what the Critical Path was.