Final answer:
The polymer ball sinks to the bottom of the vegetable oil due to its lower density.
Step-by-step explanation:
The polymer ball is at the bottom of the vegetable oil because of its density. Vegetable oil is less dense than water, which means it will float on top of water. Similarly, the polymer ball is less dense than the vegetable oil, causing it to sink to the bottom. Density is a measure of how much mass is contained within a certain volume. Objects with a higher mass in a given volume will sink, while objects with a lower mass in the same volume will float or sink to the bottom.