Answer: Hi I have the answer to your problem!
Explanation:
Cardiovascular exercise is any vigorous activity that increases heart rate and respiration and raises oxygen and blood flow throughout the body while using large muscle groups of the body repetitively and rhythmically. So your answer is A.
Animals obtain nitrogen by eating plants which has absorbed nitrogen from the soil.
Answer:
Life is based on carbon; organic chemistry studies compounds in which carbon is a central element. The properties of carbon make it the backbone of the organic molecules which form living matter. Carbon is a such a versatile element because it can form four covalent bonds.
Explanation:
When the population is large and dense.
Hope this helps:)