Answer:
If limestone reacts with limestone, it can turn into a limestone. The reason behind this formation is that, both substances have the same chemical and physical properties and molecules of limestone have a strong chemical bonds between them so it is difficult to separate them from each other.
You need more context to the question, however I think I have it figured out.
Independent variable- various colors of light
dependent variable- The growth rate from each color
Did you ever figure out the answer to this? I have the same question and don't know the answer.