Since there are 6 different cookies, the cookies can be A, B, C, D, E, F
If we select a pair of 2 different cookies, they can be AB and BC
We can see that AB and BA would be the same pair. Thus, order does not matter. When selecting items, if order doesn't matter, we apply combination. The number of possible combinations of r items from a total of n items is expressed as
nCr = n!/(r!(n - r)!
In this case,
n = 6
r = 2
6C2 = 6!/(2!(6 - 2)! = 720/(2 x 24) = 720/48
6C2 = 15
Option B is correct