**Core Concept**
Rituximab is a monoclonal antibody that targets the CD20 antigen on B cells, leading to their depletion and subsequent therapeutic effects in various B-cell disorders. It is a chimeric antibody, meaning it is composed of both human and murine (mouse) protein sequences.

**Why the Correct Answer is Right**
Rituximab's pharmacokinetics are not dose-independent, meaning its clearance and half-life are affected by the dose administered. This is because rituximab is primarily cleared by the reticuloendothelial system, and higher doses can saturate this system, leading to non-linear pharmacokinetics. This is in contrast to dose-independent pharmacokinetics, where the drug's clearance and half-life remain constant across different dose levels.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is true. Rituximab is indeed a chimeric monoclonal antibody that targets the CD20 antigen on B cells.
**Option B:** While infusion reactions can occur with rituximab, they are not the most common side effect. The most common side effects are actually infusion-related reactions, but also fatigue, nausea, and neutropenia.
**Option C:** This statement is true. Rituximab was the first FDA-approved drug for the treatment of resistant lymphomas, specifically follicular lymphoma and diffuse large B-cell lymphoma.

**Clinical Pearl / High-Yield Fact**
Rituximab's mechanism of action involves direct and indirect effects on B cells, including complement-dependent cytotoxicity, antibody-dependent cellular cytotoxicity, and apoptosis. Understanding these mechanisms is crucial for optimizing treatment outcomes and minimizing adverse effects.

**Correct Answer:**
✓ Correct Answer: D. Dose independent pharmacokinetics