**Core Concept**
Hyaluronic acid is a type of mucopolysaccharide, also known as glycosaminoglycan, that plays a crucial role in maintaining the structure and hydration of connective tissue. It is a negatively charged polysaccharide composed of repeating disaccharide units of glucuronic acid and N-acetylglucosamine.

**Why the Correct Answer is Right**
Hyaluronic acid is widely distributed throughout the body, particularly in the skin, cartilage, and synovial fluid. It is responsible for maintaining the viscoelastic properties of these tissues, enabling them to withstand mechanical stress and maintain their shape. In the skin, hyaluronic acid helps to retain moisture and maintain its suppleness, while in the joints, it reduces friction and facilitates smooth movement.

**Why Each Wrong Option is Incorrect**
**Option A:** While hyaluronic acid is present in the skin, it is not exclusive to this tissue. Other tissues, such as cartilage and synovial fluid, also contain high concentrations of hyaluronic acid.
**Option B:** Hyaluronic acid is not a type of collagen. While both are important components of connective tissue, they have distinct structures and functions.
**Option C:** Hyaluronic acid is not a type of glycoprotein. While glycoproteins are carbohydrate-protein complexes, hyaluronic acid is a polysaccharide composed of repeating disaccharide units.

**Clinical Pearl / High-Yield Fact**
Hyaluronic acid is often used in dermatological and ophthalmological applications, such as in fillers for wrinkle reduction and in eye drops for dry eye syndrome.

**Correct Answer: C. Connective tissue**