## Discussion Forum

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

a. | g(h(D)) ⊆ D |

b. | g(h(D)) ⊇ D |

c. | g(h(D)) ∩ D = ф |

d. | g(h(D)) ∩ (B - D) ≠ ф |

Answer:g(h(D)) ⊆ D |