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

Input: Consider Input: Problem: if the length of the longest chord of a certain circle is 10 , what is the radius of that certain circle ? 
Options: ['a ) 2.5', 'b ) 5', 'c ) 10', 'd ) 15', 'e ) 20']

Output: b


Input: Consider Input: Problem: a rectangular tiled patio is composed of 50 square tiles . the rectangular patio will be rearranged so that there will be 2 fewer columns of tiles and 4 more rows of tiles . after the change in layout , the patio will still have 50 tiles , and it will still be rectangular . how many rows are in the tile patio before the change in layout ? 
Options: a ) 5 , b ) 6 , c ) 10 , d ) 13 , e ) 28

Output: b


Input: Consider Input: Problem: there is a square with side ‘ a ’ and one octagon is inscribed in it . what will be perimeter of octagon . 
Options: ['a ) 8 a / 3', 'b ) 7 a / 3', 'c ) 5 a / 3', 'd ) a / 3', 'e ) 11 a / 3']


Output: a