**Core Concept**
Diuretics are classified based on their site of action and mechanism of action. They primarily affect renal tubular reabsorption of sodium and water, with varying effects on potassium and other electrolytes. Understanding the specific molecular targets and pathways involved is essential for selecting the appropriate diuretic in clinical scenarios.

**Why the Correct Answer is Right**
Option C states that thiazides inhibit sodium-potassium-chloride co-transporter — this is **incorrect**. Thiazide diuretics actually act by inhibiting the **sodium-chloride co-transporter (NCC)** in the distal convoluted tubule, not the sodium-potassium-chloride co-transporter. The latter is not a known physiological transporter in the kidney. The correct mechanism involves blocking NCC, leading to increased sodium and water excretion. This error makes C the false statement, and thus the correct choice in the "all are true except" question.

**Why Each Wrong Option is Incorrect**
Option A: Spironolactone is indeed a potassium-sparing diuretic, acting as an aldosterone antagonist, which reduces potassium excretion.
Option B: Mannitol is an osmotic diuretic that increases osmotic pressure in the renal tubules, preventing water reabsorption.
Option D: Acetazolamide inhibits carbonic anhydrase in the proximal tubule, reducing bicarbonate reabsorption and promoting diuresis.

**Clinical Pearl / High-Yield Fact**
Always remember: Thiazides block **NCC** (sodium-chloride co-transporter), not a sodium-potassium-chloride co-transporter. This distinction is critical for exam accuracy and clinical reasoning.

✓ Correct Answer: C. Thiazides act by inhibiting sodium-potassium chloride co-transpo