**Core Concept**
Calcification in the abdomen, especially when it overlies the spine on a lateral view, suggests a specific anatomical location. This clinical presentation is crucial in identifying the underlying pathology.

**Why the Correct Answer is Right**
The calcification is likely located in the right psoas major muscle. This muscle is a major component of the iliopsoas muscle, which is a large muscle in the lower back and abdomen. The psoas major muscle runs from the lumbar spine to the femur and is involved in hip flexion. Calcification in this muscle can be seen on an abdominal X-ray and is often associated with conditions like psoas abscess, muscle injury, or metastatic disease.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the clinical presentation described. The described calcification is not associated with the liver or gallbladder pathology.
**Option B:** This option does not match the described location of calcification. The calcification is not seen in the abdominal aorta on an AP view of the abdomen.
**Option C:** This option is not a likely diagnosis given the described location of calcification. The calcification is not associated with the appendicitis.

**Clinical Pearl / High-Yield Fact**
In cases of abdominal calcification, especially when it overlies the spine on a lateral view, consider psoas muscle calcification as a possible diagnosis. This can be associated with various conditions, including psoas abscess, muscle injury, or metastatic disease.

**Correct Answer: C.**