In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Input: Consider Input: Problem: a dog is tied to a tree by a long nylon cord . if the dog runs from the due north side of the tree to the due south side of the tree with the cord extended to its full length at all items , and the dog ran approximately 30 feet , what was the approximate length of the nylon cord e , in feet ? 
Options: a ) 30 , b ) 25 , c ) 15 , d ) 10 , e ) 5

Output: d


Input: Consider Input: Problem: the population of a city increases by 7 % per year but due to migration it decrease by 1 % per years . what will be the percentage increase in population in 3 years ? 
Options: a ) 9 % , b ) 9.10 % , c ) 27 % , d ) 12 % , e ) none of these

Output: b


Input: Consider Input: Problem: positive integer y is 50 percent of 50 percent of positive integer x , and y percent of x equals 16 . what is the value of x ? 
Options: a ) 20 , b ) 40 , c ) 80 , d ) 160 , e ) 320


Output: c