Probability problem s

Probability problem are very critical and outstanding this like questions but this type of questions are very important to gain mark in exam.

The names of 5 students from section A, 6 students from section B and 7 students from section C were selected. The age of all the 18 students was different. Again, one name was selected from them and it was found that it was of section B. What was the probability that it was the youngest student of the section B? 

A ) 1 /18

B ) 1 /15

C ) 1/ 6

D ) 1 / 12

Ans. 1/ 6 .