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: what is the smallest positive integer nn such that √ 6,480 ∗ n is a perfect cube ? 
Options: a ) 5 , b ) 5 ^ 2 , c ) 30 , d ) 30 ^ 2 , e ) 30 ^ 4
Example Output: e

Example Input: Problem: on the coordinate plane , points p and u are defined by the coordinates ( - 1,0 ) and ( 3,3 ) , respectively , and are connected to form a chord of a circle which also lies on the plane . if the area of the circle is ( 25 / 4 ) π , what are the coordinates of the center of the circle ? 
Options: ['a ) ( 1.5 , 1 )', 'b ) ( 2 , - 5 )', 'c ) ( 0,0 )', 'd ) ( 1 , 1.5 )', 'e ) ( 2,2 )']
Example Output: d

Example Input: Problem: the points a ( 0 , 0 ) , b ( 0 , 4 a - 4 ) and c ( 2 a + 1 , 2 a + 6 ) form a triangle . if angle abc = 90 , what is the area of triangle abc ? 
Options: a ) 88 , b ) 98 , c ) 108 , d ) 78 , e ) 90
Example Output:
a