The author says that Muir's writings include "poetic observations ... on the natural world."
I Reread paragraphs 4-9. What examples of poetic i
language can you find in this excerpt? Is the
i language also explanatory? Use examples from
the text to support your answer.

Circumference = 2 * pi * radius. 

The rotating sprinkler is the center and is creating the circle as said in the description. That 9 feet stream of water is then your radius. Plug in this radius to go the formula. 

2 * pi * 9 = 18pi ≈ 56.549

I guess the closest one is option C.