Subject to § 6–903 of this subtitle, a public school employer may not take or refuse to take any personnel action as reprisal against a public school employee because the employee: Discloses or threatens to disclose to a supervisor an activity, a policy, or a practice of the employer that is in violation of a law, rule, or regulation; Provides information to or testifies before any public body conducting an investigation, a hearing, or an inquiry into any violation of a law, rule, or regulation by the employer; or Objects to or refuses to participate in any activity, policy, or practice in violation of a law, rule, or regulation.