**Core Concept**
The cephalic vein is a superficial vein of the upper limb that plays a significant role in the venous drainage of the arm. It originates from the lateral end of the dorsal venous network of the hand and ascends along the lateral aspect of the forearm, eventually draining into a major venous structure.

**Why the Correct Answer is Right**
The cephalic vein drains into the axillary vein, which is a major vein that forms part of the venous system of the upper limb. The axillary vein is formed by the union of the basilic and cephalic veins, and it continues as the subclavian vein, ultimately draining into the superior vena cava. The cephalic vein's drainage into the axillary vein is an essential aspect of venous return from the upper limb.

**Why Each Wrong Option is Incorrect**
**Option A:** This space is not a correct location for the cephalic vein's termination.
**Option B:** The median cubital vein is a superficial vein that connects the cephalic and basilic veins, but it is not the primary drainage site for the cephalic vein.
**Option D:** The brachial vein is a deep vein that runs parallel to the brachial artery, but it is not the primary drainage site for the cephalic vein.

**Clinical Pearl / High-Yield Fact**
The cephalic vein's anatomy is crucial for medical procedures such as venipuncture and cannulation, where the vein is often used as an access site for intravenous therapy.

**Correct Answer: C. Axillary vein**