The circumference of a circle can be calculated using the formula C = πd, where C is the circumference and d is the diameter.
Given that the diameter is 4 ft, we can substitute this value into the formula:
C = π * 4 ft
C ≈ 12.57 ft
Out of the given options, 13 feet is the best estimation for the circumference as it is the closest estimate to the calculated value of 12.57 feet.