By nerve cells the heart has neurons and they work based on electrical potential.
C; A is false they sometimes exhibit recessive genes, B is true but not all species die from these diseases and D is also false
Different life forms adapt to their environment. Stable ecosystem creates a stable environment for life forms. In stable environment, life forms do not have to adapt all the time and their energy can be invested into other life processes, such as growth, reproduction, etc. Stability of ecosystem is important for adjoining ecosystems because that way boundaries and influences could be extended. Stable ecosystems are able to interact and both benefit from each other.
Your answer is actually "burning and digesting "
