**Core Concept**
Metastasis of prostate cancer refers to the spread of cancer cells from the primary site in the prostate gland to distant locations in the body. The most common sites for metastasis are those with rich blood supply and lymphatic drainage, allowing cancer cells to easily spread.

**Why the Correct Answer is Right**
Prostate cancer most commonly metastasizes to the bones, particularly to the axial skeleton, which includes the vertebral bodies, pelvis, and ribs. This is due to the hematogenous spread of cancer cells through the bloodstream, where they are carried by the venous drainage from the prostate gland. The bone microenvironment provides a favorable site for prostate cancer cells to grow and metastasize.

**Why Each Wrong Option is Incorrect**
**Option A:** Lymph nodes are a common site for metastasis in many cancers, but they are not the most common site for prostate cancer metastasis.
**Option B:** Liver metastasis is more common in cancers that spread through the portal vein, such as colorectal cancer, but it is not a typical site for prostate cancer metastasis.
**Option C:** Lung metastasis is a common site for many cancers, but it is not the most common site for prostate cancer metastasis.

**Clinical Pearl / High-Yield Fact**
Prostate cancer metastasis to bone is often accompanied by the development of osteoblastic lesions, which can be detected on bone scans and X-rays.

**Correct Answer:** D. Bones.