I'll give you a question, please answer with step-by-step reasoning process.
What includes both a person and a jellyfish?\nOptions:\n- humanity\n- headache\n- nature\n- natural world\n- society

natural world
All kinds of living beings exist in their own ecosystems.

Ecosystems are made up of all natural things around a living being.

All ecosystems together form the natural world.

Humans and jellyfish are kinds of living beings existing in the natural world.

.

Thus, the answer is natural world