A student can answer any 2 of 7 questions. In how many ways can she make a choice?

Answer 1

This is 7C2 these are combinations not permutations since order does not matter. For example picking question 1 first and then question 2 would be the same as picking question 2 first and then question1

Anyway 7C2= 7!( (7-2)!(2!)=(7x6)/2=21