Answer:
Option A, Archimedes principle
Step-by-step explanation:
According to Archimedes principle, a body which is immersed into any fluid either completely or partially, displaces certain amount of water beneath its surface. This displaced water usually exerts an upward force on the immersed object which is equal to the weight of the body which acts at the center of gravity of the displaced fluid.
Option A, Archimedes principle