A Respiration by animals CO2 is being added.
B trees burning same
C tree leaves removed
D oil added
Answer:
D
Explanation:
If a group of organs working together is called an organ system, and there are about 11 major body systems including the nervous system, the nervour system must be an organ system.
<span>Secondary succession is faster than primary succession because the soil is already there and the soil usually contains many seeds.</span>
