C
Step-by-step explanation:
Circumference can be found using
c=d
We know the circumference is 18, so we can substitute it in
18=d
We want to find d, so we have to isolate it.
To do this, divide both sides by pi
d=5.72957795131
Rounded to the nearest hundreth
d=5.73
Diameter is 5.73 inches, or choice C