If 11 boys meet at a reunion and each boy shakes hands exactly once with each of the others, then what is the total number of handshakes  Choose the correct choice from the following:
A) 55
B) 42
C) 43
D) 44
E) 45

Rationale: "n ( n - 1 ) / 2 = 11 * 10 / 2 = 55 answer : a"
Answer: A