1. The amount of light that enters a camera is proportional to the area of a circular opening behind the lens that is exposed when the shutter is open. The area is adjusted by controlling the radius of an iris diaphragm. Let A = the amount of light that enters the camera, and r = the radius of the iris diaphragm. The values of A and r are related by a function. Which statement is true about that function? A The domain of the function is the set of possible values of A, which is the dependent variable.
B The domain of the function is the set of possible values of A, which is the independent variable.
C The domain of the function is the set of possible values of r, which is the independent variable.
D The domain of the function is the set of possible values of r, which is the dependent variable.