Answer:
Reproduction is the ability of living organisms to give rise to new individuals of the same species.
Respiratory system includes all the structures and organs of living organisms associated with the process of taking oxygen into the body and giving out carbon dioxide and water vapour into the environment.
Kilograms I think I might be wrong but that's what I think.
C. When there is an equal number of molecules on each side
I think calcium but i could be wrong
