A, B, D, and E are correct.
What makes these a function and the others not is that for each x value, there is only one y value. For C, for example, there are multiple y values for the x value of -2. The same goes for F.
Answer:
Polynomial is an expression of more than two algebraic terms, especially the sum of several terms that contain different powers of the same variable(s).
The common denominator would be 18. So, 5/6 becomes 15/18 and 7/9 becomes 14/18
I not that good with math but I would say C.