Detailed Instructions: In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
Q: Problem: 3 , 14,39 , _ ? 
Options: a ) 81 , b ) 82 , c ) 83 , d ) 84 , e ) 85
A:
d