Answer:
Graph B
Step-by-step explanation:
In a function every input must have at excatly one output.
Last year my teacher taught us to use the "vertical line test", the vertical line test is if you draw a vertical (up and down) line anywhere on your graph it should only cross the graphed equation at max on spot. Since graph B is a vertical line, of you used the vertical line test there ot would cross the graphed line in infinitely many spots which is definitely more than one.
