**Core Concept**
Bevacizumab is a recombinant humanized monoclonal antibody that targets vascular endothelial growth factor (VEGF), a key mediator of angiogenesis. By inhibiting VEGF, bevacizumab disrupts the formation of new blood vessels that tumor cells need to grow and metastasize.

**Why the Correct Answer is Right**
Bevacizumab is used in combination with chemotherapy for the treatment of metastatic breast cancer, especially in patients with HER2-negative disease. The addition of bevacizumab has been shown to improve progression-free survival and overall response rates in patients with breast cancer. This is because breast cancer cells often express VEGF receptors, making them susceptible to bevacizumab's anti-angiogenic effects.

**Why Each Wrong Option is Incorrect**
**Option B:** Bevacizumab is not typically used for the treatment of gastric cancer, although it may be used in some clinical trials. The primary treatment for gastric cancer usually involves chemotherapy and surgery.

**Option C:** While bevacizumab is used in the treatment of non-small cell lung cancer (NSCLC), this is not the correct answer because the question specifically asks about carcinoma of the breast. Bevacizumab is often used in combination with chemotherapy for advanced NSCLC.

**Option D:** This option is incorrect because bevacizumab is indeed used for the treatment of breast cancer, making option A the correct choice.

**Clinical Pearl / High-Yield Fact**
Bevacizumab's anti-angiogenic effects can lead to adverse effects such as hypertension, proteinuria, and thromboembolic events. It is essential to monitor patients closely for these potential side effects when using bevacizumab in combination with chemotherapy.

**✓ Correct Answer: A. Breast**