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: sand is poured into a box so that the box is being filled at the rate of 3 cubic feet per hour . if the empty rectangular box is 5 feet long , 4 feet wide , and 3 feet deep , approximately how many hours does it take to fill the box ? 
Options: a ) 14 , b ) 16 , c ) 18 , d ) 20 , e ) 22
d

Problem: if the sides of a triangle are 30 cm , 28 cm and 12 cm , what is its area ? 
Options: a ) 120 cm 2 , b ) 112 cm 2 , c ) 776 cm 2 , d ) 666 cm 2 , e ) 168 cm 2
e

Problem: the radii of two cones are in ratio 2 : 1 , their volumes are equal . find the ratio of their heights . 
Options: ['a ) 1 : 4', 'b ) 1 : 3', 'c ) 1 : 2', 'd ) 1 : 5', 'e ) none of these']

a