36 people {a1, a2, ..., a36} meet and shake hands in a circular fashion. In other words, there are totally 36 handshakes involving the pairs, {a1, a2}, {a2, a3}, ..., {a35, a36}, {a36, a1}. Then size of the smallest set of people such that the rest have shaken hands with at least one person in the set is	Pick one:
A) 11	B) 12	C) 13	D) 15	E) 18

Rationale: if we take person a 1 in the set then it will cover a 36 and a 2 for shaking hand . similarly if we take person a 4 in the set then it will cover a 5 and a 3 for shaking hand and so on , so minimum 12 persons are required . answer : b
Answer: B