A rope of which a calf is tied is increased from 10 m to 20 m, how much additional grassy ground shall it graze?	Choose the correct choice from the following.
A) 540  B) 128  C) 100  D) 942  E) 942.86

Rationale: "π ( 202 – 102 ) = 942.86 answer : e"
Answer: E