The best experimental setup to investigate the connection between kinetic energy (related to the temperature of the water) and the behavior of the food coloring would be:
Placing one drop of food coloring in a cup with 50 mL of water at 10ºC; placing one drop of food coloring in a second cup with 50 mL of water at 40ºC.
This setup allows for a direct comparison between the diffusion of food coloring in colder water (10ºC) and warmer water (40ºC). The difference in how quickly the food coloring spreads in each temperature will illustrate the relationship between temperature and the kinetic energy of the water molecules, providing insight into how temperature affects the motion of particles in a liquid.