In my research I figured out that it would be the 4th one
        
             
        
        
        
Rivers usually empty into oceans. Any pollution deposited or pick-up by the river, will eventually end up in the ocean.
        
             
        
        
        
Answer:
The correct option is A
Countercurrent multiplication is the process whereby energy is used to generate an osmotic gradient in which water is reabsorbed from the tubular fluid to produced concentrated urine.
Explanation:
Countercurrent multiplication moves sodium chloride from tubular fluid into interstitial space deep within the kidneys. The concurrent multiplication process build up osmotic gradient interstitial fluid in a single effect. Here, sodium chloride is driven by active transport out of the tubular fluid in the thick ascending limb into the interstitial fluid, which becomes hyperosmotic. This result to water moving passively down its concentration gradient out of the tubular fluid in the descending limb into the interstitial space to a point where it attains a state of equilibrium. 
Therefore,the correct option is A, where the ions leaves the ascending limb to make water comes out of descending limb.
 
        
             
        
        
        
The energy from cellular respiration comes from food and air. The reactants first cellular respiration are oxygen and glucose. Glucose is a form of sugar and comes from food, and oxygen is found in air.
The main reactants or cellular respiration, as stated above, are oxygen and glucose.
During the first stage of cellular respiration, which takes place in the cytoplasm, a small amount of energy is produced when glucose is broken down into smaller particles.