**Core Concept**
The question is testing the knowledge of the largest protein in the human body, which is a key concept in biochemistry and cell biology. This question assesses the student's understanding of the structure and function of proteins, specifically the largest protein in the human body.

**Why the Correct Answer is Right**
The correct answer is **Fibrillin-1**, a glycoprotein that is a major component of elastic fibers found in connective tissue. Fibrillin-1 plays a crucial role in the formation and maintenance of elastic fibers, which provide elasticity and flexibility to various tissues, including skin, lungs, and blood vessels. The large size of fibrillin-1 is due to its high molecular weight, which is approximately 350 kDa.

**Why Each Wrong Option is Incorrect**
* **Option A:** **Collagen** is the most abundant protein in the human body, but it is not the largest protein. Collagen is a fibrous protein that provides structure and strength to connective tissue, but it has a smaller molecular weight than fibrillin-1.
* **Option B:** **Laminin** is a glycoprotein that is a key component of the basement membrane, but it is not the largest protein in the human body. Laminin plays a crucial role in cell adhesion and tissue development, but it has a smaller molecular weight than fibrillin-1.
* **Option C:** **Keratin** is a type of intermediate filament protein that is found in skin, hair, and nails, but it is not the largest protein in the human body. Keratin provides strength and rigidity to these tissues, but it has a smaller molecular weight than fibrillin-1.

**Clinical Pearl / High-Yield Fact**
Fibrillin-1 is associated with Marfan syndrome, a genetic disorder that affects the connective tissue and can lead to cardiovascular, skeletal, and ocular complications. Mutations in the FBN1 gene, which encodes fibrillin-1, can lead to the development of Marfan syndrome.

**Correct Answer:** C. Fibrillin-1.