Suppose that a = {2, 4, 6}, b = {2, 6}, c = {4, 6}, and d = {4, 6, 8}. identify the pairs of sets in which one is a subset of the other (in any order).

Subset A of a set B requires that all the elements of A be elements of B.
For example, {4,5} is a subset of {1,2,3,4,5} because both 4 and 5 are in {1,2,3,4,5}.  However, {2,3} is not a subset of {2,4,6,8,10} because at least one element (3) is in {2,3} but not in {2,4,6,8,10}.

Based on this, try to find the set/subset pairs.  There are three.

Ithink not so sure but i tried it out and came out to be b

Definitely