Answer:
D
Explanation:
The vertical line test is a visual way to determine if a curve is a graph of a function or not. A function can only have one output, y, for each unique input, x.
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Example: The first table is a function because each input value has only 1 output value, but the second table has more that one output value per input. (View Attached Picture Below)
The input value 4 in Table A has only 1 output value, 20. But in Table B, the input value for 4 has 2 output values, 16 and 17. So Table A is a function, while Table B is not.