Answer:
[4] Function
[5] Not a function
[6] Function
Explanation:
The vertical line test is a test to determine if the line graphed is a function. Taking a vertical line, you move it left and right through the graph. If, at any point, there are two or more intersections in the vertical line, the graph is not a function.
4 and 6 pass the test meaning they are functions, 5 does not.