0 + 1 + 2 + 3+ 4 + 5 + 6 + 7 +8 + 9 + 10 + 11 seems to equal 66. That means there are 11 + 1 = 12 people (don’t forget to count the person who shakes 0 hands)
Consecutive numbers are directly next to each other on the number line, so B is already out of the question. Add each pair together to see which one is 131.
