Here's a problem to solve: Students kept some crickets in a classroom tank. The tank was kept in an area where it would get several hours of sunlight a day. The tank contained one area with water, and another area with soil where plants were growing. From which source did the crickets gain all of their energy?

Among the 4 following options, which is the correct answer?

- A: the soil
 
- B: the water
 
- C: the plants
 
- D: the sunlight
 