I believe the answer should actually be
C.) It is a one to one function
A one to one function is a function in which the x and y values never repeat. Each value of x is different every time, and they never have the same values of y.
Positive correlation means that if x goes up then y goes up, negative correlation means that if x goes up then y goes down. Since both x and y are increasing each time, it is positive.
Answer: Choice D) 
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Work Shown:

Explanation:
First I subtracted y/b from both sides. Then I multiplied both sides by 'a' to fully isolate x. You can optionally distribute the 'a' through to each term inside the parenthesis, but your teacher has chosen not to do this.
Answer:
(
h)
Step-by-step explanation:
r = radius
h = height