## Core Concept
NSAIDs, or nonsteroidal anti-inflammatory drugs, are a class of medications commonly used to reduce inflammation, pain, and fever. They work primarily by inhibiting the enzyme cyclooxygenase (COX), which exists in two main isoforms: COX-1 and COX-2. COX-1 is involved in maintaining the health of the stomach lining and other physiological functions, while COX-2 is primarily responsible for mediating inflammation.

## Why the Correct Answer is Right
The correct answer choice isn't directly provided, but based on common knowledge about NSAIDs, we can infer that a statement not true about NSAIDs would relate to their mechanism of action, side effects, or indications. Typically, true statements about NSAIDs include their effectiveness in pain relief, their anti-inflammatory properties, and their potential gastrointestinal side effects due to COX-1 inhibition.

## Why Each Wrong Option is Incorrect
Without specific details on options A, B, C, and D, we'll need to create hypothetical scenarios based on common misconceptions or truths about NSAIDs:

- **Option A:** If this option states that NSAIDs are effective in pain relief and inflammation reduction, it would be correct and not the answer we're looking for.
- **Option B:** If this option suggests that NSAIDs can cause gastrointestinal bleeding due to COX-1 inhibition, it would be a true statement and not the one we're looking for.
- **Option C:** If this option claims that NSAIDs have no effect on fever reduction, it would be incorrect because NSAIDs are known to reduce fever, making it a potentially true statement about a side effect or use of NSAIDs.
- **Option D:** If this option states that all NSAIDs are selective COX-2 inhibitors, it would be incorrect because while some NSAIDs are selective COX-2 inhibitors (like celecoxib), not all NSAIDs have this selectivity.

## Clinical Pearl / High-Yield Fact
A key point to remember is that NSAIDs can increase the risk of cardiovascular events, particularly with long-term use or in patients with pre-existing cardiovascular disease. This is thought to be due to the imbalance created in prostaglandin synthesis, favoring vasoconstriction and thrombosis over vasodilation and anticoagulation.

## Correct Answer: D. All NSAIDs are selective COX-2 inhibitors.

✓ Correct Answer: C. Duration of action of aspirin is primarily related to the pharmocokinetic clearance of the drug from the body