Under modern contract law, an option contract:

$($a$)$ negates the offeror's power to revoke but does not nullify an offeree's attempted rejection when the offeree subsequently accepts

$($b$)$ negates the offeror's power to revoke and nullifies an offeree's attempted rejection if the offeree subsequently accepts

$($c$)$ does not negate the offeror's power to revoke

$($d$)$ negates the offeree's power to reject but does not nullify the offeror's power to revoke