How to include prompt text in multiple places in select field with Rails 3.2

Is there a way to insert text that prompts users in my select field? i.e. my dropdown for the select might look like

Select your league

NFL

NHL

NBA

MLB

Alternate leagues

EPL

La Liga

Russian PL

Is this possible in Rails 3.2 I have this code which pulls my primary choices + secondary choices... I would like a prompt before the secondary choices.

f.select("league_id", @leagues.collect {|league| [ league.name, league.id ] } + [nil] + @worldwide_leagues.collect {|league| [ league.name, league.id ] })