Definition: 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: what decimal fraction is 50 ml of a litre ? 
Options: a ) . 5 , b ) . 05 , c ) . 05 , d ) 0.05 , e ) none of these
Output:
b