**Core Concept**
Hoarseness of voice in lung carcinoma is a symptom resulting from the invasion of a specific anatomical structure. This symptom is a key clinical finding in the diagnosis of lung cancer, particularly in non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). The affected structure is closely associated with the larynx and plays a crucial role in voice production.

**Why the Correct Answer is Right**
The correct answer is related to the recurrent laryngeal nerve (RLN), a branch of the vagus nerve (cranial nerve X). The RLN is responsible for innervating the intrinsic muscles of the larynx, which are essential for voice production, respiration, and swallowing. Invasion of the RLN by lung carcinoma can lead to hoarseness of voice due to paralysis of the affected muscle. This is because the RLN supplies the cricothyroid muscle, the only intrinsic muscle that does not receive bilateral innervation, making it the most vulnerable to nerve injury.

**Why Each Wrong Option is Incorrect**
**Option A:** The phrenic nerve is responsible for innervating the diaphragm, which is not directly involved in voice production.

**Option B:** The vagus nerve is a cranial nerve that has various branches, including the RLN, but it is not the structure directly responsible for hoarseness of voice in lung carcinoma.

**Option D:** The laryngeal cartilages are structural components of the larynx but are not directly involved in the neural control of voice production.

**Clinical Pearl / High-Yield Fact**
Recall that the RLN has a long and tortuous course in the thorax, making it susceptible to injury from lung tumors, particularly those located in the mediastinum.

**Correct Answer:** C. Recurrent laryngeal nerve.