Find the cost of fencing around a circular field of diameter 18 m at the rate of Rs.2.50 a meter?  Choose the correct choice from the following.
A) 138 B) 132 C) 150 D) 140 E) 222

Rationale: "2 * 22 / 7 * 9 = 56 56 * 2 1 / 2 = rs . 140 answer : d"
Answer: D