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: the area of a parallelogram is 72 sq m and its altitude is twice the corresponding base . then the length of the base is ? 
Options: a ) 6 , b ) 16 , c ) 8 , d ) 36 , e ) none
a

Problem: a certain cube floating in a bucket of water has between 75 and 85 percent of its volume below the surface of the water . if between 9 and 16 cubic centimeters of the cube ' s volume is above the surface of the water , then the length of a side of the cube is approximately 
Options: ['a ) 4', 'b ) 5', 'c ) 7', 'd ) 8', 'e ) 9']
a

Problem: in right triangle abc , ac is the hypotenuse . if ac is 40 and ab + bc = 60 , what is the area of the triangle abc ? 
Options: a ) 225 , b ) 450 , c ) 25 √ 2 , d ) 500 , e ) 200 √ 2

d