**Core Concept**
Osteoarthritis (OA) of the knee leads to alterations in muscle strength and function around the joint, primarily due to pain and reduced mobility. The **quadriceps** and **hamstrings** are key muscle groups involved in knee stability and movement.

**Why the Correct Answer is Right**
In osteoarthritis of the knee, the **quadriceps muscle**, especially the **vastus medialis**, is often the first to undergo wasting. This is because the quadriceps plays a crucial role in stabilizing the knee joint and absorbing shock during weight-bearing activities. Pain and decreased mobility associated with OA lead to disuse atrophy of the quadriceps.

**Why Each Wrong Option is Incorrect**
**Option A:** Not specified, assuming it's not quadriceps.
**Option B:** Not the primary muscle affected first.
**Option C:** Not the initial muscle to waste in OA knee.
**Option D:** Not the correct answer as per the given context.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that early strengthening of the quadriceps can help alleviate symptoms and potentially slow the progression of osteoarthritis in the knee.

**Correct Answer:** D. Quadriceps.