These linear functions are in the form: y = ax + b
Plugging in any value of x will give you the value of y, and vice-versa.
The grid says that when x = 0, y = 1.35. And also, when x = 22.5, y = 0.
So you can eliminate half of the possibilities by plugging x = 0 in all the equations.
When x = 0, y = ax + b is simply y = b. So only A. and B. make sense so far.
When y = 0, y = ax + b is simplifies to 0 = ax + b which simplifies to ax = -b. By plugging x = 22.5, you should be able to deduce which of the answers is right. I can confirm if you'd like
The distance around a rectangle or a square is as you might remember called the perimeter. The distance around a circle on the other hand is called the circumference. It is calculated as follows:
C = 2pi(r)
From this, we can solve for r and evetually solve for the diameter.
