Final answer:
Loop diuretics are considered high-ceiling diuretics and they work by inhibiting the reabsorption of Na+ and Cl- in the loop of Henle, thereby increasing urine output and helping to treat hypertension.
Step-by-step explanation:
The diuretic agent that is considered a "high-ceiling" diuretic is c. Loop diuretics. These medications are potent agents that significantly increase the excretion of Na+ and Cl- ions by the ascending limb of the loop of Henle, which enhances urine output. Thus, they are effective in treating conditions such as hypertension and congestive heart failure. The reason these diuretics lead to increased urination is due to their inhibition of sodium and chloride reabsorption, which carries water with it osmotically, leading to increased urine volume.