**Core Concept**
The ulnar nerve is a branch of the brachial plexus, originating from the C8 and T1 nerve roots, and is responsible for innervating various muscles and providing sensation to the medial aspect of the forearm and hand. Understanding the anatomy and function of the ulnar nerve is crucial for diagnosing and managing nerve injuries.

**Why the Correct Answer is Right**
The ulnar nerve primarily supplies the flexor carpi ulnaris (D) and the flexor digitorum profundus (not mentioned in the options), but it does not supply the flexor digitorum superficialis (C). Instead, the median nerve is responsible for innervating the flexor digitorum superficialis. The ulnar nerve does pass through the cubital tunnel (B), which is a narrow anatomical passageway at the elbow that can cause compression of the nerve. The ulnar nerve originates from the C8 and T1 nerve roots (A), making this option correct.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is a correct statement, as the ulnar nerve does indeed originate from the C8 and T1 nerve roots.
**Option B:** This option is a true statement; the ulnar nerve does pass through the cubital tunnel.
**Option C:** This option is incorrect, as the ulnar nerve does not supply the flexor digitorum superficialis; instead, the median nerve provides innervation.
**Option D:** This option is a true statement; the ulnar nerve does supply the flexor carpi ulnaris.

**Clinical Pearl / High-Yield Fact**
The cubital tunnel syndrome, caused by compression of the ulnar nerve at the elbow, can lead to symptoms such as numbness, tingling, and weakness in the hand, particularly affecting the fourth and fifth fingers.

**✓ Correct Answer: C. Supply flexor digitorum superficialis**