**Horner's Syndrome Components**

**Core Concept**
Horner's syndrome is a neurologic disorder characterized by the disruption of sympathetic nerve supply to the face and eye on one side of the body. It involves a combination of clinical features due to the impaired sympathetic innervation of the eye and face.

**Why the Correct Answer is Right**
Horner's syndrome typically consists of three main components:
- **Ptosis** (drooping of the eyelid) due to the loss of sympathetic innervation to the superior tarsal muscle ( Müller's muscle).
- **Miosis** (constricted pupil) resulting from the interruption of sympathetic fibers to the dilator pupillae muscle.
- **Anhidrosis** (absence of sweating) in the face on the affected side, caused by the loss of sympathetic innervation to the sweat glands.

**Why Each Wrong Option is Incorrect**
**Option A:** This is a correct component of Horner's syndrome.
**Option B:** This is a correct component of Horner's syndrome.
**Option C:** This is a correct component of Horner's syndrome.

**Clinical Pearl / High-Yield Fact**
To remember the components of Horner's syndrome, use the mnemonic "PTA" for Ptosis, Miosis, and Anhidrosis.

**Correct Answer: D.**