Final answer:
The incorrect advice to give a parent would be to introduce solids before six months. The recommended practices are to begin at six months, introduce one new food at a time, and watch for allergies.
Step-by-step explanation:
The advice that would NOT be good to give to a parent regarding the introduction of solids to their six-month-old infant is d) Introduce solids before six months. The best practices for introducing solids to an infant include starting at about six months of age, introducing one new food at a time, and monitoring for allergic reactions.
Introducing a variety of solid foods all at once can make it difficult to identify any potential allergens and can overwhelm the infant's developing digestive system. Moreover, introducing solids before six months is generally not recommended as infants are not developmentally ready and it may increase the risk of food allergies and other health issues.