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:
2.
Step-by-step explanation:
1+1=2
We are given the following equation:

Subtract both sides by 17

Take the positive/negative square root of both sides

This should be your answer. Let me know if you have any questions, thanks!
The graph of the relation between x and y is as shown in attached figure
By applying the vertical line test we find that the relation is not a function because there are two points which are (1,-1) , (1,3) have the same value of x with different values of y which contradicts with with the rule of function.
So we want to know what do we need to measure to determine the wavelength of the wave on the image. A wavelength is the distance between peaks of the wave. More generally, the distance on which the wave shape repeats. So on the image we need to measure X to determine the wavelength. So the correct answer is X.