Multi-choice problem: Continue writing the next sentence in this paragraph:

How to determine your primary health insurance as a dependent on both plans
Determine whether the rule covers your situation.
The " birthday rule " is used to determine which health insurance plan is primary if you are a dependent on both plans, but it only applies to children.
If you are a minor, you can use the birthday rule to determine your primary health insurance plan.

OPTIONS:
(a). While an adult needs the birthday rule, a minor means you cannot enroll in another plan. That qualifies you as a dependent (which is very rare in the united states).
(b). The rule also may apply if you are over the age of 18, but you're a college student and still considered a dependent of your parents. Find out the birthdays of your parents.
(c). For children under 6 months of age, your child's primary insurance is dependent on your primary medical or dental insurance. If you are a minor, you cannot use the birthday rule.
(d). This applies if you are a minor and do not have any dependents. Children under the age of 13 can then " parent " the plans that their baby cannot buy or the plan that their doctor can buy.
(b).