At what points during the year are fish—which need a large amount of dissolved oxygen—most likely to be evenly distributed throughout the water of a lake that freezes over in winter? (4 points)

Select one:
a. Spring and fall when warm and cold water mixes
b. Fall and winter when the water is warmer
c. Summer and winter when warm water settles on the bottom
d. Spring and summer when the cold water settles on top

answer: c.

explanation:

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.