The formula for the circumference \( C \) of a circle is given by:
\[ C = \pi \times d \]
where \( d \) is the diameter of the circle. In this case, the diameter is 4 feet.
Using the value of \( \pi \) (approximately 3.14), we can calculate the circumference:
\[ C = \pi \times 4 \approx 3.14 \times 4 \approx 12.56 \text{ feet} \]
Therefore, the best estimation for the circumference from the options given is:
13 feet.