What is the probability of randomly selecting one of the shortest diagonals from all the diagonals of a regular decagon (10-sided polygon)?	Choose the correct choice from the following answers:
A) 3/10 B) 2/5 C) 2/7 D) 10/21 E) 5/11
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 2/7.
<result>C</result>
What is the probability of randomly selecting one of the shortest diagonals from all the diagonals of a regular decagon (10-sided polygon)?