(a) A public security or an interest coupon may be executed, with or without a seal, with a manual or facsimile signature.
(b) The signature on a public security or on an interest coupon of a person who is no longer an officer when the security or coupon is delivered to a purchaser is valid and sufficient for all purposes.
(c) A person's successor in office may complete the execution, authentication, or delivery of the public security or interest coupon.