Here's a problem to solve: A student planted two bean seeds in two identical pots containing the same type of soil. He placed one pot in a closet and the other near a sunny window. Each day, he poured 15 milliliters of water into each pot. Which factor was different for the two pots?

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

- A: amount of water
 
- B: amount of light
 
- C: type of soil
 
- D: type of seed
 