**Core Concept**
The skin over the pinna (auricle) is a unique anatomical structure due to its embryological development from six hillocks of His. This distinct origin influences the skin's characteristics and potential pathologies.

**Why the Correct Answer is Right**
The skin over the pinna is thin and lacks sebaceous glands, hair follicles, and sweat glands. This absence is a result of the skin's developmental origin from the first and second pharyngeal arches, which do not give rise to these structures. Additionally, the pinna's skin is innervated primarily by sensory nerve fibers from the vagus nerve (cranial nerve X), explaining the characteristic sensitivity to touch and temperature changes.

**Why Each Wrong Option is Incorrect**
* **Option A:** This is incorrect because the skin over the pinna does not contain sebaceous glands or hair follicles, unlike most other areas of the body.
* **Option B:** This is incorrect as the skin over the pinna does not contain sweat glands, which are present in other areas of the body.

**Clinical Pearl / High-Yield Fact**
The skin over the pinna is a common site for basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), which are types of skin cancer. This is due to the skin's thinness and lack of melanocytes, making it more susceptible to UV radiation damage.

**Correct Answer: C. Thinning of skin with lack of sebaceous glands and hair follicles.**