Which of the following body fluids is NOT considered potentially infectious?

Urine from healthy individuals is typically not considered potentially infectious because it generally does not contain pathogens when the person is free from illness. In a healthy person, urine is usually sterile, meaning it does not harbor bacteria, viruses, or other infectious agents that could be transmitted to others. This characteristic distinguishes it from the other body fluids listed.

In contrast, saliva, breast milk, and blood can all transmit infectious diseases. Saliva can carry pathogens such as those responsible for colds and flu, and certain viruses like HIV. Breast milk can also transmit infections such as HIV. Blood is widely recognized as a significant vector for various pathogens, including Hepatitis B, C, and HIV. Therefore, urine from healthy individuals is typically excluded from the category of potentially infectious body fluids, making it the correct answer to the question.