36-20 At a party in Washington, each man shakes hands with everyone except his own spouse, but the women do not shake hands with each other. If 13 couples attend the party, then the total number of handshakes among these 26 people is
(A) 78.
(B) 185.
(C) 234.
(D) 312.
(E) 325.
(41st American High School Mathematics Examination, 1990)
［Solution］ There are 26 participants in total. Since each of the 13 men shakes hands with the remaining 24 people (excluding their own spouse), there are a total of 13 * 24 handshakes. However, the handshakes between any two men are counted twice, so these should be subtracted.
Moreover, the women do not shake hands with each other, so the total number of handshakes is
$$
13 \cdot 24 - C_{13}^{2} = 312 - 78 = 234 \text{ (times). }
$$

Therefore, the answer is $(C)$