Tough and Tricky questions: Combinations.
If 11 persons meet at a reunion and each person shakes hands exactly once with each of the others, what is the total number of handshakes?
A) 11 10 9 8 7 6 5 4 3 2 1
B) 10 9 8 7 6 5 4 3 2 1
C) 11 10
D) 55
E) 45
Kudos for a correct solution.
Source: Chili Hot GMAT