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

Ex Input:
Problem: the diameter of a circle is 4 / π . find the circumference of the circle . 
Options: ['a ) 8', 'b ) 4 π', 'c ) 4', 'd ) 6', 'e ) 5']

Ex Output:
a


Ex Input:
Problem: the length of a rectangular plot is thrice its breadth . if the area of the rectangular plot is 867 sq m , then what is the breadth of the rectangular plot ? 
Options: ['a ) 19 m', 'b ) 17 m', 'c ) 10 m', 'd ) 12 m', 'e ) 18 m']

Ex Output:
b


Ex Input:
Problem: a square mirror has exactly half the area of the rectangular wall on which it is hung . if each side of the mirror is 21 inches and the width of the wall is 28 inches , what is the length of the wall , in inches ? 
Options: a ) 21.5 , b ) 31.5 , c ) 41.5 , d ) 61.5 , e ) 71.5

Ex Output:

b