The circumference \( C \) of a circle can be calculated using the formula:
\[ C = \pi \times d \]
where \( d \) is the diameter. Given that the diameter is 4 feet, we can calculate the circumference as follows:
\[ C = \pi \times 4 \]
Using an approximation for \( \pi \) (approximately 3.14), we can estimate:
\[ C \approx 3.14 \times 4 = 12.56 \text{ feet} \]
Now, we can look at the options provided: 25, 50, 6, and 13. The best estimation for the circumference, which we calculated to be approximately 12.56 feet, is 13.