1. A student notices that wearing darker colors in sunlight makes him feel warmer, so he decides to conduct an experiment. He takes five pieces of different-colored cloth and wraps each one around a water bottle. He then places all five bottles in direct sunlight and measures the temperature of the water in each bottle an hour later.
What should be kept constant throughout this experiment?
O the color of the cloth
O the temperature of the water
the amount of water in each bottle
O the temperature of the outside air