21. A public body may refuse to release or to confirm the existence of information if, as a result of its disclosure, borrowings, proposed borrowings, transactions or proposed transactions relating to property, services or works, a proposed tariffing, taxation or imposition of dues, or proposed amendments to taxes or dues would be revealed, where such disclosure would likely(1) unduly benefit or seriously harm a person, or
(2) have a serious adverse effect on the economic interests of the public body or group of persons under its jurisdiction.