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

Problem: the ratio of 2 numbers is 10 : 20 and their h . c . f . is 100 . their l . c . m . is ? 
Options: a ) 1100 , b ) 3000 , c ) 2100 , d ) 1000 , e ) 2000
e