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'.
Q: Problem: 8 men can dig a pit in 20 days . if a man works half as much again a s a boy , then 4 men and 9 boys can dig a similar pit in :
Options: a ) 10 days , b ) 12 days , c ) 15 days , d ) 16 days , e ) 20 days
A:
d