Describe a math tool you could use to determine if a relation is a function. Explain how you would use it. Select all that apply.

Multiple select question

A)
I could use a mapping diagram. If more than one arrow points from an input value to the output values, I know it is not a function.

B)
I could use a straight object like a pencil. If the pencil intersects a graph at more than one point when it is held vertically, I know it is not a function.

C)
I could use a table. If I see that there is more than one output for an input, then the relation is a function.

D)
I could use a straight object like a pencil. If the pencil intersects a graph at more than one point when it is held horizontally, I know it is not a function.

E)
I could use a mapping diagram. If more than one arrow points from an output value to the input values, I know it is not a function.