Question

How many pairs of sets \((S, T)\) are possible among the subsets of \(\{1,2,3,4,5,6\}\) that satisfy the condition that \(S \subseteq T\)?

• A. 729
• B. 728
• C. 665
• D. 664

Hint:

When counting subsets with \(S \subseteq T\), think element-wise. Each element has 3 options (in T only, in both S and T, or in neither).