Respuesta :

A. Not a function because it's a circle that doesn't pass the vertical line test

B. Not a function because we have x = 4 repeated more than once. Same for x = 9 as well.

C. Not a function. Any vertical line fails the vertical line test. Any vertical line is therefore not a function.

D. This is a function since it passes the vertical line test.

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In summary, the final answer is choice D

D is the correct answer the other person who answered explains why.