May an employee be terminated for: (a) declining to agree to a document delineating certain obligations to their employer in relation to their spouse's work on behalf of a competing company, after being promised they would not be terminated as a result of their spouse's employment with a competing firm; (b) communicating with an insurance adjuster against their employer's instructions about certain fire safety violations committed by their employer; (c) complaining about being underpaid in violation of the Fair Labor Standards Act and state law; (d) opposing an employer's treatment of employees who are entitled to claim workers' compensation benefits; (e) soliciting signatures for a letter denouncing his or her employer's management; or (f) bringing a personal injury action against their employer?