Okay, let's tackle this question. The question is about which monoclonal antibody causes cardiomyopathy. First, I need to recall the monoclonal antibodies used in various treatments and their side effects.

Monoclonal antibodies are used in oncology, autoimmune diseases, etc. Some are known for specific adverse effects. For example, trastuzumab (Herceptin) is a monoclonal antibody used in HER2-positive breast cancer. I remember that trastuzumab can cause cardiotoxicity, including cardiomyopathy and heart failure. It's a well-documented side effect, so that's a key point here.

Now, looking at other monoclonal antibodies: bevacizumab (Avastin) is an anti-VEGF agent used in various cancers. Its main side effects are hypertension, bleeding, and gastrointestinal perforation, not cardiomyopathy. Rituximab (Rituxan) targets CD20 in B-cells, used in lymphomas and autoimmune diseases, but its main side effects are infusion reactions and hypoglycemia. Adalimumab (Humira) is a TNF inhibitor for rheumatoid arthritis, with side effects like infections and injection site reactions, not cardiomyopathy.

So the correct answer should be trastuzumab. The core concept here is the adverse effects of monoclonal antibodies, specifically cardiotoxicity. The clinical pearl is that trastuzumab is associated with left ventricular dysfunction, which is a high-yield fact for exams. The other options don't have cardiomyopathy as a known side effect. Need to make sure I explain why each wrong option is incorrect, focusing on their actual side effects versus the question's focus on cardiomyopathy.

**Core Concept**
Monoclonal antibodies can induce cardiotoxicity via mechanisms like HER2 receptor inhibition or immune-mediated myocarditis. Trastuzumab, a HER2-targeting monoclonal antibody, is classically associated with dose-dependent cardiomyopathy due to impaired cardiac myocyte function.

**Why the Correct Answer is Right**
Trastuzumab inhibits HER2 receptors in breast cancer cells but also affects HER2 signaling in cardiomyocytes. HER2 is critical for cardiac contractility; its suppression leads to reduced Akt phosphorylation and mitochondrial dysfunction, causing left ventricular dysfunction. This cardiotoxicity is reversible in early stages but may progress to irreversible cardiomyopathy if continued.

**Why Each Wrong Option is Incorrect**
**Option A:** Bevacizumab (anti-VEGF) causes hypertension and proteinuria, not cardiomyopathy.
**Option B:** Rituximab (anti-CD20) is linked to infusion reactions and hypogammaglobulinemia.
**Option C:** Adalimumab (anti-TNF) may cause hepatotoxicity or reactivation of latent TB, not cardiac myopathy.

**Clinical Pearl / High-Yield Fact**
Trastuzumab-induced cardiomyopathy is a high-yield exam topic. Always monitor LVEF before and during therapy. The mnemonic **"Trastuzumab = Heart Trouble"** reinforces this association.

**Correct Answer: C. Trastuzumab**

✓ Correct Answer: A. Trastuzumab