Instructions: 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'.
Input: Problem: 6 people can do work in 80 days how much people they required to complete the work in 16 days ? 
Options: a ) 10 , b ) 20 , c ) 30 , d ) 40 , e ) 50
Output:
c