Answer: C) No, because one x-value corresponds to two different y values.
Here we have x = 3 correspond to y = 4 and y = 3 at the same time.
A function is only possible if any x input leads to exactly one y output. Put another way, we can't have x repeating any values if we want a function.
If you plot the points from the table, then you'll see the graph fails the vertical line test and that's a visual way to see we don't have a function.