**Core Concept**
Secondary deposits from carcinoma breast are a common complication of breast cancer, often resulting from hematogenous spread to distant organs. The metastatic process involves the invasion of cancer cells into the bloodstream, which are then filtered out by the lungs, liver, and other organs.

**Why the Correct Answer is Right**
The correct answer is based on the fact that the liver is a common site for metastasis due to its rich blood supply and high metabolic activity. The liver filters the blood from the digestive tract and detoxifies substances, making it an ideal location for cancer cells to settle and proliferate. The liver's unique anatomy, with its sinusoidal structure and high levels of Kupffer cells, also facilitate the seeding and growth of metastatic cells.

**Why Each Wrong Option is Incorrect**
**Option A:** Bone is a common site for metastasis, but it is not the most common site for breast cancer metastasis. While bone metastases can be painful and debilitating, they are not the primary destination for breast cancer cells.
**Option B:** The lungs are a common site for metastasis due to their high blood flow and lack of lymphatic drainage. However, they are not the most common site for breast cancer metastasis.
**Option C:** The brain is a rare site for metastasis from breast cancer, and it is not a common location for secondary deposits.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that breast cancer metastasis often follows a predictable pattern, with the liver, lungs, and bone being the most common sites. This knowledge can help clinicians diagnose and manage metastatic disease more effectively.

**Correct Answer: C. Lungs.**