A director, officer, or agent of a nonprofit association is not liable for a contractual obligation of the association unless one of the following conditions is satisfied:
(a) The director, officer, or agent expressly assumes responsibility for the obligation in a signed writing that specifically identifies the obligation assumed.
(b) The director, officer, or agent executes the contract without disclosing that the director, officer, or agent is acting on behalf of the association.
(c) The director, officer, or agent executes the contract without authority to execute the contract.