**Core Concept**
Anterolateral arthroscopy of the knee is a surgical procedure that involves inserting an arthroscope through an incision in the anterolateral aspect of the knee, allowing for visualization and treatment of intra-articular lesions. This procedure is typically performed to diagnose and treat various knee pathologies, including meniscal tears, ligamentous injuries, and osteochondral defects.

**Why the Correct Answer is Right**
The anterolateral portal is chosen for arthroscopy of the knee because it provides a direct visualization of the anterior and posterior horns of the menisci, as well as the anterior cruciate ligament (ACL). This portal is also useful for treating lesions in the anterolateral aspect of the knee, such as meniscal tears or osteochondral defects. The anterolateral portal is created by making a small incision in the anterolateral aspect of the knee, through which the arthroscope is inserted.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the anterolateral portal is not typically used for arthroscopy of the posterior aspect of the knee. While the anterolateral portal can provide some visualization of the posterior aspect of the knee, it is not the most optimal portal for this purpose.
**Option B:** This option is incorrect because the anteromedial portal is typically used for arthroscopy of the knee, but it is not the primary portal used for anterolateral arthroscopy. The anteromedial portal is often used in conjunction with the anterolateral portal for a more comprehensive evaluation of the knee joint.
**Option C:** This option is incorrect because the posterolateral portal is not typically used for arthroscopy of the knee. This portal is often used for arthroscopy of the shoulder or other joints, but it is not commonly used for knee arthroscopy.
**Option D:** This option is incorrect because the posteromedial portal is not typically used for arthroscopy of the knee. This portal is often used for arthroscopy of the shoulder or other joints, but it is not commonly used for knee arthroscopy.

**Clinical Pearl / High-Yield Fact**
When performing anterolateral arthroscopy of the knee, it is essential to carefully evaluate the patient's anatomy and identify the optimal portal for visualization of the lesion. A thorough understanding of the knee anatomy and the optimal portal locations is crucial for successful arthroscopic surgery.

**Correct Answer: C.**