The correct option is C 55
Method 1:
If there are n people in a group,The first person shakes hands with a total of (n-1) persons, the second with (n-2) persons and so on.
So, total no. of handshakes =(n−1)+(n−2)+(n−3)+.....+2+1.=(n×(n−1))×2
Here, n=11.
So, the total no. of handshakes =(11×10)2=55
Method 2 (Using Combinations)
Total no. of handshakes = no. of ways of selecting 2 people out of n.
= nC2
=11C2
=(11×10)1×2=55