In administering the plan, the officers and employees of the system shall discharge their duties with respect to the plan solely in the interest of the participants and beneficiaries:
(a) In accordance with the documents and instruments governing the plan insofar as those documents and instruments are consistent with this part.
(b) For the exclusive purpose of both of the following:
(1) Providing benefits to participants and their beneficiaries.
(2) Defraying reasonable expenses of administering the plan.
(c) By investing with the care, skill, prudence, and diligency under the circumstances then prevailing that a prudent person acting in a like capacity and familiar with those matters would use in the conduct of an enterprise of a like character and with like aims.