Check if each of the following is a function: 1. Mapping diagram with Input: -2, 0, 1 and Output: -1, 0, 2,...

Check if each of the following is a function:
1. Mapping diagram with Input: -2, 0, 1 and Output: -1, 0, 2, 3
2. Table with x: -1, 0, 1, 2 and y: 0, 2, 4, 8
3. Set of ordered pairs: {(-5, 1), (-2, 0), (0, 3), (5, 1)}
4. Graph with plotted points