Does the graph of the equation $x^2 + y^2 = 25$ represent a function?

Yes, because for every x-value, there is a y-value.

No, because a vertical line like $x=3$ intersects the graph at two points.

No, because the graph is not a straight line.

A car rental service charges a 50 dollar flat fee plus 0.20 dollars per mile driven. In this relationship, which of the following is the dependent variable?

The 0.20 dollar per-mile charge

Yes, because both points have an x-value of 2.

No, because the y-values are different.

No, because the input $x=2$ corresponds to more than one output.

Yes, because the points are symmetrical.