An option in poker is a chance for the big blind to raise or check if the preflop pot has remained unraised. If the pot has already been raised before the action gets to the big blind, they will be facing a raise and won’t have an option.
Option Poker Example:
You’re playing in the big blind position, and the action has been limped around the table to you. You have the option of raising or checking, so you decide to end the pre-flop betting round by choosing the latter.