Final answer:
Infants can have their first full immersion or bathing once the umbilical cord stub has fallen off, which is usually within three weeks after birth.
Step-by-step explanation:
When considering when an infant can have immersion or bathing, it is important to wait until the umbilical cord stub has dried out, shriveled, darkened, and spontaneously fallen off. This process typically takes about three weeks after birth. Option 'd. Once the cord falls off' is the most appropriate time for the infant's first full immersion bath to ensure proper healing of the navel area and to prevent potential infection.
The umbilical cord is cut immediately after birth, but the stub that is left behind is still sensitive and requires care. Until it falls off, sponge baths are recommended to keep the infant clean. Once the umbilical cord stub has fallen off, the resulting navel area is sufficiently healed to tolerate submersion in water.