An environmental group claims that a local chemical plant is polluting a nearby river. They are calling for a shutdown of the chemical plant. The evidence that would help you the most in evaluating the claim would be (A) a repeated study that shows chemicals produced by the plant are in water harming fish or other wild life. (The answer is A.)
They leave no record of their existence because it's rare that fossils form. You need the right conditions in which the animal's remains are covered in silt, dirt, and rock layers in order for a fossil to form and therefore preserve the animal's remains in rocks. Otherwise, the animal's remains will be eaten by other animals or eventually rot away.
The respiratory and circulatory systems work with each other in this manner, the respiratory system will obtain oxygen then the circulatory system brings the oxygen to different parts of the body then it also takes carbon dioxide from different tissues of the body and bring carbon dioxide to lungs then the respiratory system takes carbon dioxide outside the body during exhalation
