## **Core Concept**
The question assesses the understanding of pharmacokinetic properties of various Nonsteroidal Anti-Inflammatory Drugs (NSAIDs), specifically their ability to penetrate tissues and concentrate in synovial fluid. This property is crucial for the effectiveness of NSAIDs in treating inflammatory conditions such as arthritis.

## **Why the Correct Answer is Right**
Diclofenac is known for its excellent tissue penetrability. It has a high degree of lipophilicity, which allows it to easily cross cell membranes and accumulate in tissues, including inflamed joints. Consequently, diclofenac achieves significant concentrations in synovial fluid, which is beneficial for treating conditions like rheumatoid arthritis. Its ability to penetrate tissues and concentrate in synovial fluid makes it an effective option for managing inflammatory pain.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While some NSAIDs have moderate tissue penetration, specific details about Option A are not provided, making it difficult to directly refute. However, based on the correct answer being Diclofenac, we can infer that Option A does not possess the same level of tissue penetrability as Diclofenac.
- **Option B:** Similarly, without specifics on Option B, we acknowledge that it is not recognized for the same level of synovial fluid concentration as Diclofenac.
- **Option C:** This option is incorrect because the correct answer is specified as Option D, implying that Options C does not have the same pharmacokinetic profile as Diclofenac regarding tissue penetration and synovial fluid concentration.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that Diclofenac's high lipophilicity contributes to its good tissue penetrability and high concentration in synovial fluid, making it particularly effective for treating joint-related inflammatory conditions. This characteristic is a significant advantage in the management of arthritis and similar conditions.

## **Correct Answer:** D. Diclofenac.