You'd need to find the distance AROUND the garden, which is also PERIMETER.
To find the perimeter of a circle, you use the following equation:
[tex]2 \pi r[/tex]
[tex]2 \pi (4)[/tex] = [tex]8 \pi [/tex]
[tex]8 \pi [/tex] = 25.13 ft
I don't know what your answer options are, but chose the option closest to 25.13 ft