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

Example Input: Problem: the slant height of a cone is 21 cm and radius of the base is 10 cm , find the curved surface of the cone .
Options: a ) 330 , b ) 770 , c ) 660 , d ) 100 , e ) 600
Example Output: c

Example Input: Problem: if paint costs $ 3.20 per quart , and a quart covers 60 square feet , how much will it cost to paint the outside of a cube 10 feet on each edge ?
Options: a ) $ 1.60 , b ) $ 32.00 , c ) $ 96.00 , d ) $ 108.00 , e ) $ 196.00
Example Output: b

Example Input: Problem: if y is the smallest positive integer such that 1260 multiplied by y is the square of an integer , then y must be
Options: a ) 25 , b ) 35 , c ) 60 , d ) 75 , e ) 140
Example Output:
b