In this task, you need to provide the correct option for a given problem on probability from the provided options.
Q: Problem: in how many ways can 11 books on english and 9 books on french be placed in a row on a shelf so that two books on french may not be together ? 
Options: a ) 220 . , b ) 240 , c ) 260 , d ) 280 , e ) 300
A: 
a