In this task, you need to provide the correct option for a given problem from the provided options.

Example Input: Problem: there are 180 doctors and nurses at a hospital . if the ratio of doctors to nurses is 2 to 3 , how many nurses are at the hospital ? 
Options: a ) 100 , b ) 104 , c ) 108 , d ) 112 , e ) 116
Example Output: c

Example Input: Problem: in a certain alphabet , 16 letters contain a dot and a straight line . 30 letters contain a straight line but do not contain a dot . if that alphabet has 50 letters , all of which contain either a dot or a straight line or both , how many letters contain a dot but do not contain a straight line ? 
Options: a ) 4 , b ) 8 , c ) 12 , d ) 16 , e ) 20
Example Output: a

Example Input: Problem: there are 12 slate rocks , 16 pumice rocks , and 8 granite rocks randomly distributed in a certain field . if 2 rocks are chosen at random and without replacement , what is the probability that both rocks will be slate rocks ? 
Options: a ) 3 / 32 , b ) 7 / 64 , c ) 11 / 105 , d ) 15 / 127 , e ) 19 / 134
Example Output:
c