Select all of the true statements. A.
π is the circumference of a circle whos diameter equals 1.

B.
π is the constant of proportionality relating the diameter of a circle to its circumference.

C.
π is the area of a circle whose diameter equals 1.

D.
π is the circumference of a circle whose radius equals 1.

E.
π is the area of a circle whose radius equals 1.

F.
π is the constant of proportionality relating the radius of a circle to its area.