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 rectangular window is twice as long as it is wide . if its perimeter is 18 feet , then what are its dimensions in feet ? 
Options: ['a ) 3 / 2 by 7 / 2', 'b ) 5 / 3 by 10 / 3', 'c ) 2 by 4', 'd ) 3 by 6', 'e ) 10 / 3 by 20 / 3']
d

Problem: find the circumference and area of radius 6 cm . 
Options: ['a ) 113 cm ²', 'b ) 144 cm ²', 'c ) 154 cm ²', 'd ) 184 cm ²', 'e ) 194 cm ²']
a

Problem: the mass of 1 cubic meter of a substance is 400 kilograms under certain conditions . what is the volume , in cubic centimeters , of 1 gram of this substance under these conditions ? ( 1 kilogram = 1,000 grams and 1 cubic meter = 1 , 000,000 cubic centimeters ) 
Options: a ) 0.8 , b ) 1.25 , c ) 8.0 , d ) 2.5 , e ) 80.0

d