Question

check the box for those graphs that are not functions.
check if graph a is not a function.
check if graph b is not a function.
check if graph d is not a function.
check if graph c is not a function.

Explanation:

Step1: Apply Vertical Line Test to A

Any vertical line intersects A at 1 point. So A is a function.

Step2: Apply Vertical Line Test to B

Any vertical line intersects B at 1 point. So B is a function.

Step3: Apply Vertical Line Test to C

A vertical line intersects C at 2 points. So C is not a function.

Step4: Apply Vertical Line Test to D

A vertical line intersects D at 2+ points. So D is not a function.

Answer:

Check if graph C is not a function.
Check if graph D is not a function.