**Core Concept**
A Baker's cyst, also known as a popliteal cyst, is a fluid-filled swelling that occurs in the back of the knee. It is associated with knee joint pathology, particularly osteoarthritis, and is thought to result from the communication between the knee joint and the gastrocnemius-semimembranosus bursa.

**Why the Correct Answer is Right**
The Baker's cyst forms due to the communication between the knee joint and the gastrocnemius-semimembranosus bursa, allowing the synovial fluid from the knee joint to seep into the bursa. This fluid accumulation leads to swelling and is often associated with knee joint inflammation, such as osteoarthritis. The cyst is usually palpable and can cause pain and limited mobility in the knee.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as Baker's cyst is not typically associated with the quadriceps tendon. The quadriceps tendon is located in the front of the knee and is not directly related to the formation of a Baker's cyst.

**Option B:** This option is incorrect as Baker's cyst is not typically associated with the medial meniscus. While the medial meniscus is a structure within the knee joint, the Baker's cyst is more closely related to the communication between the knee joint and the gastrocnemius-semimembranosus bursa.

**Option C:** This option is incorrect as Baker's cyst is not typically associated with the lateral meniscus. Like the medial meniscus, the lateral meniscus is a structure within the knee joint, but it is not directly related to the formation of a Baker's cyst.

**Clinical Pearl / High-Yield Fact**
A Baker's cyst is often associated with knee joint inflammation, such as osteoarthritis, and can be diagnosed through a combination of physical examination and imaging studies, including ultrasound or MRI.

**Correct Answer: C. The popliteal space.**