#### Answer

(a) Function
(b) Not a Function
(c) Function
(d) Not a Function

#### Work Step by Step

(a) Each element of A is matched with exactly one
element of B, so it does represent a function.
(b) The element 1 in A is matched with two elements,
–2 and 1 of B, so it does not represent a function.
(c) Each element of A is matched with exactly one
element of B, so it does represent a function.
(d) The element 2 in A is not matched with an element
of B, so the relation does not represent a function.