So abiotic means nonliving, so the only abiotic option is B. the gravel on the bottom of the aquarium.
Teak surfing is an activity that could lead to carbon monoxide poisoning. It is a water sport (illegal) wherein the person holds onto any part of a powerboat (such as the swim platform, swim deck, swim step, or swim ladder) while being dragged through the water. The boat may create a suction behind it and can trap exhaust fumes behind the boat, which can cause carbon monoxide poisoning to the person holding on to the boat.
Answer:
A control group is a set standard so that comparisons can be made to see what your experiment did. The experimental group is the group that has been changed. A control group also allows you to determine your variables.
Explanation:
