The neuron, or the impulse-conducting cell of nervous tissue.
The answer is D. i past this class with a 98 overall score.
A group of organs would be an organ system so perhaps B
Answer:
they were a paracite
Explanation:
the mitochondrial theorem or something. basically they live in a symbiotic relationship but originally it was two separate life forms. this is true for the mitochondria and chloroplasts