Answer:
- Functions - a and c
- Non- function - b
Explanation:
This is verified with a vertical line test.
If a graph of a function is intersected by a vertical line at more than one point, it is not a function. This comes from the definition of a function.
We can see that the graphs a and c pass the vertical line test but the graph b fails, since at any positive x, the vertical line has two - y coordinates per each x- coordinate.