The best experimental setup to investigate the connection between kinetic energy and temperature 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 you to compare the diffusion of the food coloring in water at two different temperatures (10ºC and 40ºC). The higher temperature (40ºC) will increase the kinetic energy of the water molecules, which should result in a faster diffusion of the food coloring compared to the lower temperature (10ºC). This directly demonstrates the relationship between temperature and kinetic energy.