**Core Concept**
Osteosarcoma is a primary malignant bone tumor characterized by abnormal bone formation, leading to a distinct radiographic appearance. The X-ray features of osteosarcoma are crucial for early diagnosis and can be categorized into several types, including Codman's triangle, sunburst pattern, and "onion skin" appearance.

**Why the Correct Answer is Right**
Osteosarcoma typically presents with a Codman's triangle, which is a triangular area of new bone formation caused by the tumor's growth into the surrounding soft tissue. This is due to the periosteum's attempt to repair the bone defect created by the tumor. The sunburst pattern is another characteristic feature, resulting from the rapid growth of the tumor, which causes the bone to be pushed outward in a radiating fashion. The "onion skin" appearance is also common, representing layers of new bone formation as the periosteum is lifted and new bone is deposited.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is likely incorrect because osteosarcoma does not typically present with a lytic (bone-destroying) appearance on X-ray, unlike some other bone tumors.
**Option B:** This option may be incorrect because osteosarcoma is more likely to cause a sclerotic (bone-forming) appearance rather than a purely lytic appearance.
**Option C:** This option is likely incorrect because osteosarcoma typically does not present with a mixed sclerotic and lytic appearance, although this can occur in other bone tumors.

**Clinical Pearl / High-Yield Fact**
The "Codman's triangle" is a classic radiographic feature of osteosarcoma and should be remembered as a key diagnostic clue. This characteristic appearance is often seen in the early stages of the disease and can be an important factor in making the diagnosis.

**Correct Answer: A.**