The birthday rule is used to determine the primary insurance policy when the patient is: a. Insured by her own employer and her spouse's employer b. A child covered by two or more plans c. Injured in a collision with the policyholder's vehicle d. Injured at his or her place of employment

B. A child covered by two or more plans

Explanation:

The birthday rule is used to determine the primary insurance policy when the patient is "A child covered by two or more plans."

The purpose is to determine which of the parent's plan comes as primary or secondary. Hence, the birthday rule stipulates that the parent, either father or mother whose day of birth, that is month and day, comes first in the year will be assigned as the primary coverage for the child or patient.

For example, assuming a Father's birthday is August, 23rd and that of the Mother is February 7th, then the Mother's plan is considered as the primary coverage, while that of the Father will be considered as secondary coverage for the child.