Answer:
B
Step-by-step explanation:
For a function to be true, there cannot be any same x value for two different y value. Therefore, B, there is the same x value for 4 but with 2 different ys, 4 and 1.
B.
It is B because it contains a one-to-many relation.
4 maps to 4 and also 4 maps to 1.
