If I were you I would choose muscles it seems right to me although I might be wrong. Hope this helped some! ;)
Any characteristic, whether a physical trait, a behaviour, a physiological adaptation etc can make an organism more or less likely to survive in a particular environment.
A dark colour could help a rabbit survive if it lives in a dark forest, because predators can't see it so well, but it would be less likely to survive in the arctic, where the environment is all white and it would show up.
In terms of the characteristics, think about: does it help the organism get food? Does it help protect the organism from predators? If it does, that organism is more likely to survive, and pass the characteristic on to it's offspring. If a bacterium has a characteristic of not being killed by antibiotics, this will help it to survive and breed.
Answer:
A
Explanation:
Homeostasis' main job is to keep your body balanced, typically with variable factors such as temperature or enzyme amounts. Your heart rate increases to keep your blood pressure steady while you exercise. This way, you can have a relatively balanced blood pressure as you exhilarate yourself.
Photosynthesis? Its when a plant takes in sunlight for ATP (energy).
