**Question:** True about synovial membrane of the knee joint is -

A. It secretes synovial fluid
B. It is only present in the hip joint
C. It is a single layer of cells
D. It only functions as a barrier

**Core Concept:**
Synovial membrane is a thin, single-layered membrane that covers the articular surfaces of the bones in synovial joints. It forms the inner lining of the joint cavity, producing synovial fluid which serves as a lubricant, reducing friction between the bones and providing nutrients to the articular cartilage.

**Why the Correct Answer is Right:**
Synovial membrane secretes synovial fluid, which plays a crucial role in reducing friction between the bones and maintaining joint health. This vital function makes the correct answer A true.

**Why Each Wrong Option is Incorrect:**
B is incorrect because synovial membrane is found in multiple joints, not just the hip. Option C is false as the synovial membrane is a multiple-layered membrane, not a single layer of cells. Option D is incorrect because synovial membrane not only acts as a barrier but also secretes synovial fluid for joint health maintenance.

**Clinical Pearl / High-Yield Fact:**
The knee joint is a common site for synovial membrane to be found. Understanding the key role of synovial membrane in producing synovial fluid is essential for maintaining joint health and preventing conditions like osteoarthritis.