A nurse is teaching a prenatal class about infection prevention at a community center. Which of the following statements by a client indicates an understanding of the teaching?

A. Hand washing for at least 20 seconds with warm water and soap is recommended to prevent infection, not just 10 seconds. B. Pregnant women should avoid cleaning the cat's litter box due to the risk of toxoplasmosis. C. Chickenpox is contagious until all lesions have crusted, so visiting a person with chickenpox is only safe 5 days after the lesions crust over. D. Antibiotics are not effective for viral infections and should not be taken unless prescribed for a bacterial infection.