<span>The correct answer is B. their kidneys can't excrete concentrated salt. Since salt is dissolved in water, the organism sends its water reserves to the kidneys to dissolve and excrete the salt but this leads to dehydration. That's why people at sea who don't know what they're doing often dehydrate themselves by drinking sea water, thinking that they're safe.</span>
The correct answer that would best complete the given statement above would be CELL RESPIRATION and FOSSIL FUELS. Carbon dioxide enters the atmosphere by animal and human cell respiration and the burning of fossil fuels. Human activities such as BURNING FOSSIL FUELS and RESPIRATION cycle carbon through the carbon cycle. Hope this is the answer that you are looking for.