If A = { 1, 2 }, then which is true?

{2} ⊆ A

{2} ∈ A

{2} ⊆ P(A)

None of these

P(A) is the power set of A = {1, 2}, which includes all subsets: ∅, {1}, {2}, {1, 2}.

So, {2} is one of the subsets, hence it is an element of P(A).