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 Q]: Problem: 80 pie square inches of material of negligible thickness are required to construct a 1 / 16 scale model of a cylindrical barrel . if the diameter of the base of the barrel is 160 inches , then what is the volume of the barrel , to the nearest cubic foot ? 
Options: ['a ) 2 pie', 'b ) 11 pie', 'c ) 178 pie', 'd ) 711 pie', 'e ) 1280 pie']
[EX A]: c

[EX Q]: Problem: if the radius of a circle is decreased 20 % , what happens to the area ? 
Options: a ) 10 % decrease , b ) 20 % decrease , c ) 36 % decrease , d ) 40 % decrease , e ) 50 % decrease
[EX A]: c

[EX Q]: Problem: the radius of a cone is 10 m , height 21 m . the volume of the cone is : 
Options: ['a ) 2200', 'b ) 1100', 'c ) 5500', 'd ) 3300', 'e ) 1050']
[EX A]:
a