Final answer:
The circumference of the key ring is 8π centimeters.
Step-by-step explanation:
The circumference of a circle can be calculated using the formula:
C = 2πr
Given that the radius of the key ring is 4 centimeters, substitute this value into the formula:
C = 2π(4) = 8π centimeters.
Therefore, the circumference of the key ring is 8π centimeters.