A letter offering to sell property to sitting tenants with a response deadline does not create a right of pre-emption or option unless there is a concluded subsidiary contract binding the offeror to keep the offer open for the specified period. Such a letter, particularly when it states that the offer is made "if you are interested in doing so," constitutes merely an invitation to treat or offer to negotiate, not a binding option. An offeror is entitled to withdraw such an offer before acceptance, and once rejected (expressly or impliedly), the offer lapses and cannot subsequently be accepted. For associations or artificial persons, a deponent's authority to institute proceedings on behalf of members may be established by reference to the organization's constitution without requiring individual supporting affidavits from all members.