Answer:
Container 2
Step-by-step explanation:
Out of all the water containers, ball in 2nd container is floating because it has ocean water.
Ocean water has a huge amount of salt in it and a saline water has greater density than fresh water, bottled water or tap water. So if you will drop a golf ball inside the container of ocean water, it will eventually float as density of golf ball is less that density of ocean water.
Same theory helps to explain why bodies do not sink in ocean, rather float on its surface.