Subject to subsection (b) of this section, an employee of a participating governmental unit who is a member of one of the employees’ systems is entitled to the benefits to which State employees are entitled under that system. An employee of a participating governmental unit that has elected to participate in: the contributory pension benefit option under § 31-116 of this subtitle shall be subject to Title 23, Subtitle 2, Part II of this article; or the Alternate Contributory Pension Selection under § 31-116.1 of this subtitle shall be subject to Title 23, Subtitle 2, Part III of this article. An employee of a participating governmental unit that has not elected to participate in: the contributory pension benefit option under § 31-116 of this subtitle is not subject to Title 23, Subtitle 2, Part II of this article; or the Alternate Contributory Pension Selection under § 31-116.1 of this subtitle is not subject to Title 23, Subtitle 2, Part III of this article.