The correct answer is D. After a Waiting period.
A pre-existing condition is a health problem that you had before you applied for health insurance. Some health insurance plans exclude coverage for pre-existing conditions, or they may only cover them after you have been a member of the plan for a certain amount of time, called a waiting period.
The waiting period for pre-existing conditions is usually 6 months, but it can be longer. If you have a pre-existing condition, it is important to check with your health insurance plan to find out when you will be covered for it.
Options A, B, and C are incorrect because they are not ways in which pre-existing illnesses could be covered. Option A is incorrect because a pre-existing illness cannot be covered after it is cured. Option B is incorrect because a pre-existing illness cannot be covered before it is contracted. Option C is incorrect because a pre-existing illness cannot be covered after it is diagnosed.