Q37

Let $f : A \to B$ be an injective (one-to-one) function. Define $g : 2^A \to 2^B$ as: $g(C) = \left \{f(x) \mid x \in C\right\}$, for all subsets $C$ of $A$. Define $h : 2^B \to 2^A$ as: $h(D) = \{x \mid x \in A, f(x) \in D\}$, for all subsets $D$ of $B$. Which of the following statements is always true?