Final answer:
According to the Model Group Coordination of Benefits provision, the employer's plan is considered the primary plan when a person is covered by multiple group health plans.
Step-by-step explanation:
The Model Group Coordination of Benefits provision determines which health insurance plan is considered the primary plan when a person is covered by multiple group health plans. In this case, M is covered by both his employer's group health plan and his spouse's group health plan. According to the Model Group Coordination of Benefits provision, M's employer's plan is considered the primary plan when he files a claim.