Answer:
yes!!!
Explanation:
Short explanation. The same y value can be true for many "exs". But the same x value can only have ONE y value to define a function. So if you draw y = 0.5 across that graph that you have given us, you get many x values that have 0.5 as a y value.
If on the other hand, you draw a line of x = 1, there is only 1 value that y has and that is zero.
This is a function.