Really really really really need on this don't understand at all in a rush

Ohohoh combinations

cominations comes in factorials
formula = 4! / (4! - 2! ) 2!
the ! means the number, and the list of numbers below it like 3! means 1*2*3
so lets solve this
4! / (4! - 2! ) 2! = 4! / 2! 2! =
1*2*3*4 / 1*2 2! =
3*4 / 2! (2! is 1*2 )=
12 / 2 = 6
there are six combinations to choose from

The correct answer is: b