Answer:
See below.
Explanation:
To be a function the graph must pass the vertical line test. If any of the vertical lines which can be drawn intersects the graph more than once then it's not function.
So Graph 1 is not a function because a vertical line passes through the 2 points in quadrant 1, whereas Graph 2 is a function because any vertical line you can draw only passes through the graph once.
Graph 3 - not a function.
Graph 4 - not a function.
Graph 5 - not a function.
Graph 6 is a function.