which of the following of a circle is always smaller than the other two?

A the circumference
B the diameter
C the radius
D it depends on the size of the circle

C)radius

circumference = 2*Pi*radius
Diameter = 2*radius

Since Pi is approximately 3,14, the circumference is approximately 6,28 times bigger than the radius.

The diameter is 2 times as big as the radius