What is the probability of randomly selecting one of the shortest diagonals from all the diagonals of a regular decagon (10-sided polygon)? Select
A) 3 / 10	B) 2 / 5	C) 2 / 7	D) 10 / 21	E) 5 / 11

Rationale: from any vertex , there are two vertices on sides , which do not make a diagonal but a side . so the remaining n - 3 vertices make diagonals . there are 2 of these diagonals which are the shortest . the probability of choosing one of the shortest diagonals is 2 / 7 . the answer is c .
Answer: C