Final answer:
The probable sign of ballottement is the presence of palpable fetal parts.
Step-by-step explanation:
Ballottement is a technique used by healthcare professionals to assess the presence of floating structures, such as the fetus, within the uterus during a physical examination. It involves tapping the cervix or playing gentle pressure on the abdomen to observe the movement of the fetus. The presence of palpable fetal parts is a probable sign of ballottement, as it indicates that the fetus is freely moving within the amniotic fluid. Therefore, option 2) Palpable fetal parts is the probable sign of ballottement.