What does mean the 'also' keyword in the request statement of dhclient-ethX.conf?

Issue

What does mean the 'also' keyword in the request statement of dhclient-ethX.conf?
What is the difference between the following two?

option rfc3442-classless-static-routes code 121 = array of unsigned integer 8;
request rfc3442-classless-static-routes;

option rfc3442-classless-static-routes code 121 = array of unsigned integer 8;
also request rfc3442-classless-static-routes;