Final answer:
The number of elements in set a is the same as the number of elements in set b.
Step-by-step explanation:
The number of elements in set a is 6 because there are 6 elements in the set {1, 2, 3, 4, 5, 6}. To determine the number of elements in set b, we count the elements in the set {2, 4, 6, 8, 10}. Similarly, b also has 6 elements. Therefore, the number of elements in a is the same as the number of elements in b.
So, the answer is 2) a.