**Core Concept**
Sclerotic skeletal metastasis refers to the spread of cancer to the bones, resulting in increased bone density and sclerosis. This type of metastasis is often associated with certain types of cancer that produce factors that stimulate osteoblasts, leading to increased bone formation.

**Why the Correct Answer is Right**
Breast cancer is the most common cause of sclerotic skeletal metastasis in female patients. The metastatic cells from breast cancer produce parathyroid hormone-related protein (PTHrP), which stimulates osteoblasts to produce new bone matrix, resulting in sclerotic lesions. This process is mediated through the parathyroid hormone receptor 1 (PTHR1) on osteoblasts, leading to increased bone density and sclerosis.

**Why Each Wrong Option is Incorrect**
**Option A:** Although prostate cancer can cause sclerotic metastasis, it is more common in male patients. In females, prostate cancer metastasis to the skeleton is rare.
**Option B:** Renal cell carcinoma can cause lytic skeletal metastases, but it is not typically associated with sclerotic lesions.
**Option C:** Lung cancer can cause both lytic and sclerotic skeletal metastases, but it is not the most common cause of sclerotic metastasis in female patients.

**Clinical Pearl / High-Yield Fact**
When evaluating a patient with sclerotic skeletal metastasis, it's essential to consider breast cancer as a primary source, especially in female patients. A thorough review of the patient's medical history, including previous surgeries and treatments, can help identify the underlying cause.

**Correct Answer: C. Breast cancer.**