**Core Concept**
The anatomical snuff box is a triangular deepening on the radial, dorsal aspect of the hand, formed by the tendons of the thumb muscles and the radius bone. Its boundaries are important for clinical examination and diagnosis of various conditions.

**Why the Correct Answer is Right**
The boundaries of the anatomical snuff box are formed by the tendons of the extensor pollicis brevis (EPB) and abductor pollicis longus (APL) muscles, and the radius bone. The EPB tendon forms the medial border, the APL tendon forms the lateral border, and the radius bone forms the floor of the snuff box. The base of the thumb (radial styloid process) forms the apex.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a boundary of the anatomical snuff box.
**Option B:** This option is not a boundary of the anatomical snuff box.
**Option D:** This option is not a boundary of the anatomical snuff box.

**Clinical Pearl / High-Yield Fact**
The boundaries of the anatomical snuff box are crucial for diagnosing conditions such as De Quervain's tenosynovitis, which affects the tendons of the EPB and APL muscles.

**Correct Answer:** A.