In this task, you need to provide the correct option for a given problem on probability from the provided options.

Problem: in how many ways can 21 books on english and 19 books on hindi be placed in a row on a shelf so that two books on hindi may not be together ?
Options: a ) 1540 , b ) 2314 , c ) 5420 , d ) 1240 , e ) 4512
a