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: a sporting good store sells one type of baseball bat and one type of baseball . the cost for 2 bats and 4 balls is $ 220 . the cost for 1 bat and 6 balls is $ 190 , as well . if someone were to buy an equal number of bats and balls , at most how many bats can he purchase if he has a budget of $ 270 for the purchase ? 
Options: a ) 1 , b ) 2 , c ) 3 , d ) 4 , e ) 5
Example Output: c

Example Input: Problem: a and b are two circles . the radius of a is four times as large as the diameter of b . what is the ratio between the areas of the circles ? 
Options: ['a ) 1 : 8 .', 'b ) 1 : 2 .', 'c ) 1 : 24 .', 'd ) 1 : 64 .', 'e ) 1 : 6 .']
Example Output: d

Example Input: Problem: a rectangular tank needs to be coated with insulation . the tank has dimensions of 3 feet , 5 feet , and 2 feet . each square foot of insulation costs $ 20 . how much will it cost to cover the surface of the tank with insulation ? 
Options: a ) $ 1100 , b ) $ 1240 , c ) $ 1360 , d ) $ 1480 , e ) $ 1550
Example Output:
b