A mapping diagram shows a relation, using arrows, between input and output for the following ordered pairs: (negative 3, negative 4), (0, negative 4), (negative 2, 2), (negative 2, negative 1), (1, negative 3), (3, 7).
Which ordered pair needs to be removed in order for the mapping to represent a function?

(–3, –4)
(–2, –1)
(1, –3)
(3, 7