Final answer:
A nurse hearing fetal heart tones below the maternal umbilicus would likely expect a breech presentation, with the baby's buttocks or feet positioned towards the birth canal. Most breech births today are delivered via Caesarian section.
Step-by-step explanation:
If a nurse assessing fetal heart tones hears them best below the level of the maternal umbilicus, the fetal presentation that would be most likely is breech presentation. This is because the baby's buttocks or feet are positioned to enter the birth canal first as opposed to the head, which is the norm in cephalic presentation. During a breech birth, the heart tones will frequently be audible at or below the mother's umbilicus, since that is where the baby's chest would be located in this presentation. Nowadays, most breech births result in a Caesarian section for delivery due to the potential risks associated with vaginal delivery of a breech baby.