What should the nurse's response be when the guardian of a child with varicella asks when their child can safely return to school? A) "The child can return to school when all the lesions are crusted over." B) "The child can return to school after 48 hours of starting antiviral medication." C) "The child can return to school as soon as they start feeling better." D) "The child can return to school immediately; varicella is not contagious."