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

Problem: a box measuring 25 inches long by 30 inches wide by 15 inches deep is to be filled entirely with identical cubes . no space is to be left unfilled . what is the smallest number of cubes that can accomplish this objective ? 
Options: a ) 80 , b ) 82 , c ) 84 , d ) 88 , e ) 90
e

Problem: the sides of a rectangle are in the ratio of 6 : 5 and its area is 1331 sq . m . find the perimeter of rectangle . 
Options: a ) 121 , b ) 123 , c ) 125 , d ) 122 , e ) 126
a

Problem: how many books each of volume 200 meter cube can be packed into a crate of volume 4000 meter cube ? 
Options: a ) 20 , b ) 40 , c ) 60 , d ) 80 , e ) can not be determined

e