A Kingdom. There's an animal and a plant Kingdom.
Answer:
the smallest structural and functional unit of an organism, typically microscopic and consisting of cytoplasm and a nucleus enclosed in a membrane. Microscopic organisms typically consist of a single cell, which is either eukaryotic or prokaryotic.
Explanation:
This is actually called a competition. I would describe this relationship as negative where only one benefits. Some may see it as parasitism, as one will overpower the other and benefit while it suffers.
