An expiremental constant is the amount of water and sunlight, the variable is the music
Answer:
A. the food web
Explanation:
Ecosystems have lots of different living organisms that interact with each other. The living organisms in an ecosystem can be divided into three categories: producers, consumers and decomposes. They are all important parts of an ecosystem. Producers are the green plants.
People believed that zebras were white animals with black stripes, since some zebras have white underbellies. Embryological evidence, however, shows that the animal's background color is black and the white stripes and bellies are additions.