Ms. Snyder's students were studying living things and energy. They emptied a package of yeast into a cup of warm water. Next they added .5 grams of sugar. After 15 minutes, the students noticed bubbles forming on the surface of the water. Using a dropper, they put a sample of the liquid on a glass slide and looked at the sample with a microscope. This is what they saw. The yeast cells were reproducing. Where did the yeast cells get the energy to grow and reproduce? A) They got energy from the water. B) The sugar was the energy source. C) They used sunlight and oxygen for energy. D) The yeast digested organisms found in the water.