Final answer:
The best instruction for the nurse to provide to the caregiver of the 6-year-old child with recurrent UTIs is to use plain water for the bath and shampoo the hair last in order to reduce the risk of infection.
Step-by-step explanation:
The best instruction for the nurse to tell the caregiver of the 6-year-old child diagnosed with recurrent urinary tract infections (UTIs) would be to use plain water for the bath and shampoo the hair last. This is because using plain water for the bath helps to maintain the natural balance of the child's skin and reduces the risk of irritation or infection. Shampooing the hair last minimizes the chance of any shampoo or residue coming into contact with the child's genital area, further reducing the risk of UTIs.