I'll do my best to answer this one.
For the first choice you have 5 options
You have 4 options for the second choice
You have 3 options for the third choice
You have 2 options for the fourth choice
You have 1 option for the fifth choice
5+4+3+2+1 = 15
15x5 = 75.
Either that or it might be 5! ie. 120. If anybody can validify/disprove this that would help