When an individual is covered by more than one health plan and is injured, what provision determines which plan is that person's primary coverage?

The correct answer is - coordination of benefits.

Explanation:

Coordination of benefits determine that which plan or insurance policy will have the responsibility of the primary payment and which plan will contribute in the extent of the primary plan when a person is covered by multiple medicare plan.  

So COB creates a design for two insurance companies by which they are able to pay their equal and fair share. It decides which is a primary plan and which is a secondary plan. So here the individual is covered by multiple plan so COB will determine which plan is that person's primary coverage.