Hi Peter I'm Eddie I can help you today.

This problem makes sure you understand what a function is. Be sure to understand all the answers not just wrong one.

A function is continuous means if you were to pick up your pencil when drawing it wouldn't be continuous. Also only one x corresponds to y value. To test these things simple draw a horizontal line at any point if it touches 2 point it isn't a function or one-to-one function. Try it on x^2 as you can see it passes. So D Vertical line test is your answer. If you like further assistance feel free to reach out for a first free session ok.