Final answer:
The foul-smelling red lochia of a 1 day PP patient indicates the presence of infection.
Step-by-step explanation:
The nurse determines that the foul-smelling red lochia of a 1 day PP patient indicates the presence of infection (Option B). Normally, the lochia transitions from red to a thinner, pinkish form called lochia serosa, and eventually to a creamy or watery discharge called lochia alba. A foul-smelling odor suggests the presence of an infection, which may require further evaluation and treatment.