What statement by a patient about caring for a newborn's umbilical cord indicates understanding?

The statement about washing around the umbilical cord with plain water daily indicates a proper understanding of newborn cord care. This practice aligns with healthcare guidelines which recommend keeping the cord clean and dry to prevent infection. Using plain water is advised because it minimizes irritation to the area and supports natural healing.

The other options lack the appropriate understanding of umbilical cord care. Applying petroleum jelly can trap moisture and lead to infection, while covering the cord with a bandage can hinder ventilation and is unnecessary. Allowing the cord to fall off on its own is appropriate, but it doesn't address the cleaning aspect, which is crucial for maintaining hygiene during the healing process.