Which statement about eye makeup is correct?

The statement that eyeliner and mascara should be replaced every 3 to 6 months to avoid contamination is accurate and addresses important health considerations regarding eye makeup. Over time, makeup can harbor bacteria, especially if it is not used properly or stored inappropriately. Regularly replacing products helps prevent potential eye infections and ensures that the formulations remain safe and effective. Both eyeliner and mascara are particularly prone to bacterial growth because they are applied close to the eye, an area that is sensitive and susceptible to infection.

In terms of the other options, while applying eyeliner to the inner margin is a common practice, it can lead to occlusion of the tear ducts and may introduce bacteria to the eyes. The recommendation about mascara being applied solely at the base of the eyelashes is a simplification; while it is correct to focus on the base for thicker appearance, it is often applied to the mid-length and tips as well for a more natural look. Applying makeup before inserting contact lenses can also potentially introduce particles or irritants to the eye, which can be problematic for contact lens wearers. Therefore, the recommendation to replace eye makeup regularly is the most critical for eye health.