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

[EX Q]: Problem: 9 spheres of the same size are made from melting a solid cylinder of 16 cm diameter and 12 cm height . what is the diameter of each sphere ? 
Options: ['a ) 4 cm', 'b ) 6 cm', 'c ) 8 cm', 'd ) 10 cm', 'e ) 12 cm']
[EX A]: c

[EX Q]: Problem: 42 persons can repair a road in 12 days , working 5 hours a day . in how many days will 30 persons , working 6 hours a day , complete the work ? 
Options: a ) 10 , b ) 16 , c ) 13 , d ) 14 , e ) 19
[EX A]: d

[EX Q]: Problem: if 7 men and 2 boys working together , can do 6 times as much work per hour as a man and a boy together . find the ratio of the work done by a man and that of a boy for a given time ? 
Options: a ) 2 : 5 , b ) 2 : 3 , c ) 1 : 8 , d ) 4 : 1 , e ) 3 : 2
[EX A]:
d