**Core Concept**
Athletic pubalgia, also known as sports hernia, is a condition characterized by chronic groin pain in athletes. The underlying mechanism involves a combination of muscle strain, fascial disruption, and potential inguinal canal herniation. The condition is often associated with repetitive strain on the abdominal and pelvic floor muscles.

**Why the Correct Answer is Right**
The correct answer involves the identification of the specific muscle group responsible for the strain in athletic pubalgia. The muscle group affected is the adductor magnus, adductor longus, and adductor brevis, along with the rectus abdominis and internal oblique muscles. These muscles are subjected to excessive stress and strain due to repetitive movements in sports such as soccer, hockey, and rugby. The strain on these muscles can lead to micro-tears, inflammation, and chronic pain.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as it does not specify the correct muscle group responsible for the strain in athletic pubalgia. Identifying the correct muscle group is crucial in understanding the underlying mechanism of the condition.
* **Option B:** This option is incorrect as it does not accurately describe the muscle group affected by athletic pubalgia. While the iliopsoas muscle can be involved in hip and lower back pain, it is not the primary muscle group responsible for the strain in athletic pubalgia.
* **Option C:** This option is incorrect as it does not accurately describe the muscle group affected by athletic pubalgia. The external oblique muscle is not typically involved in the strain associated with athletic pubalgia.

**Clinical Pearl / High-Yield Fact**
It's essential to note that athletic pubalgia often presents with non-specific symptoms, making diagnosis challenging. A thorough clinical examination, including palpation of the muscle groups and assessment of the inguinal canal, is crucial in diagnosing athletic pubalgia.

**Correct Answer: C.**