**Core Concept**
Pseudogout, also known as calcium pyrophosphate deposition disease (CPPD), is a type of arthritis that occurs due to the accumulation of calcium pyrophosphate dihydrate crystals within the joint space. This condition is characterized by sudden, severe joint pain and swelling, often mimicking the symptoms of gout. The **knee joint** is particularly susceptible to pseudogout due to its large size and weight-bearing function.

**Why the Correct Answer is Right**
The knee joint is the most commonly affected joint in pseudogout, accounting for approximately 50% of all cases. This is because the knee joint is subject to high levels of mechanical stress, which can contribute to the formation of calcium pyrophosphate dihydrate crystals. The **menisci** and **ligaments** within the knee joint can also provide a nidus for crystal formation, leading to inflammation and joint damage.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while other joints can be affected by pseudogout, they are less commonly involved than the knee.
**Option B:** Similarly, this option is incorrect because it is not the most frequently affected joint in pseudogout.
**Option D:** This option is also incorrect as it is not typically associated with pseudogout.

**Clinical Pearl / High-Yield Fact**
Pseudogout can be distinguished from gout by the presence of calcium pyrophosphate dihydrate crystals in the joint fluid, which can be identified using **polarized light microscopy**. This diagnostic tool is essential for confirming the diagnosis of pseudogout.

**Correct Answer:** D. Knee.