Based on the data provided (6 paper clips floating in cold water, 3 at room temperature, and 0 in hot water), the hypothesis that would best be supported is:
"If the temperature decreases, then the number of paper clips that will float on the surface will increase because the surface tension will increase."
This hypothesis aligns with the data showing that more paper clips float in cold water compared to room temperature and hot water, suggesting that lower temperatures correspond to greater surface tension, allowing more paper clips to float.