To calculate the circumference of a circle, you can use the formula:
\[ C = \pi \times d \]
where \(C\) is the circumference and \(d\) is the diameter.
Given that the diameter \(d = 4\) feet:
\[ C = \pi \times 4 \approx 3.14 \times 4 \approx 12.56 \text{ feet} \]
The best estimation for the circumference from the options provided is:
13 feet.