【单选题】Each person at a party shook hands exactly once with each of the other people at the party. There was a total of 21 handshakes exchanged at the party. Column A Column B The number of people at the par...
A.
if the quantity in Column A is greater
B.
if the quantity in Column B is greater
C.
if the two quantity are equal
D.
if the relationship cannot be determined from the information given