I mean, 1 would be fine, but then he would have her tell him the truth first. The obvious choice here is to be blunt and say that he wont initialize any sexual relationship with her while she is still lying.
...That said, we only know she is lying because it is a story. Normally one would never come to think of the idea of someone lying, and asking the helpdesk about her major is a very stalkerish move in every way, particularly as he could text her. I think she should run from him.