**Core Concept**
Trigger finger is a condition characterized by inflammation and stenosis of the tendon sheath in the hand, leading to pain, stiffness, and limited mobility of the affected finger. It occurs due to repetitive strain or trauma, causing thickening of the tendon sheath and subsequent narrowing of the pulley system.

**Why the Correct Answer is Right**
Trigger finger is caused by the inflammation of the tendon sheath, which leads to the constriction of the tendon as it passes through the pulley system. The A1 pulley, located at the level of the metacarpophalangeal joint, is the most commonly affected pulley in trigger finger. This constriction causes the tendon to snap or "trigger" as it moves, resulting in the characteristic symptoms of trigger finger.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because trigger finger is not caused by a direct injury to the tendon, but rather by repetitive strain or trauma leading to inflammation and stenosis of the tendon sheath.
* **Option B:** This option is incorrect because trigger finger is not a condition that affects the ligaments of the hand, but rather the tendon sheath and pulley system.
* **Option C:** This option is incorrect because trigger finger is not a condition that affects the nerves of the hand, but rather the musculoskeletal system.

**Clinical Pearl / High-Yield Fact**
Trigger finger is a common condition in individuals who perform repetitive activities such as typing or playing musical instruments, and can be treated with conservative measures such as rest, physical therapy, and corticosteroid injections. In severe cases, surgical release of the affected pulley may be necessary.

**Correct Answer: C. Trigger finger is a condition characterized by inflammation and stenosis of the tendon sheath in the hand, leading to pain, stiffness, and limited mobility of the affected finger.**