The root word of Unicellular already tells you the answer. Uni means only one cell. So the answer is one cell.
Some examples of important nonliving things in an ecosystem are sunlight, temperature, water, air, wind, rocks, and soil. Living things grow, change, produce waste, reproduce, and die.
the answer would be b because b is the only one that changes while a and c does not change for their type.
hope this helps! ❤ from peachimin :)