**Core Concept**
Hypernephroma, also known as renal cell carcinoma (RCC), is a type of kidney cancer that can metastasize to various sites in the body. The pattern of metastasis is an important aspect of tumor spread and affects the prognosis and treatment plan.

**Why the Correct Answer is Right**
The most common site for secondary metastasis in hypernephroma is the lungs. This is due to the direct venous drainage of the kidney into the inferior vena cava, which eventually drains into the right heart and then the pulmonary circulation. The tumor cells can break away from the primary site and travel through the bloodstream to the lungs, where they can implant and form metastases. The lungs are the first capillary bed that the tumor cells encounter after leaving the kidney, making them the most likely site for metastasis.

**Why Each Wrong Option is Incorrect**
**Option A:** The liver is a common site for metastasis in many cancers, but it is not the most common site for hypernephroma metastasis.
**Option B:** The adrenal glands are located near the kidneys and can be involved in the spread of hypernephroma, but they are not the most common site for metastasis.
**Option C:** The lymph nodes are involved in the spread of many cancers, but they are not the most common site for hypernephroma metastasis.

**Clinical Pearl / High-Yield Fact**
The lungs are the most common site for metastasis in hypernephroma due to the direct venous drainage of the kidney into the inferior vena cava. This is an important consideration in the staging and treatment of renal cell carcinoma.

**Correct Answer:** A. Lungs