Identify the mapping diagram that represents the relation and determine whether the relation is a function.
{(-2, -4), (-1, -4), (3, -4), (6, -4)}
A. This is not a function (-2, -1, 3, 6, -> -4)
B. This relation is a function (-2, -1, 3, 6, -> -4)
C. The relation is not a function (-4 -> -2, -1, 3, 6)
D. The relation is a function (-4 -> -2, -1, 3, 6)