Okay, let's tackle this question about unilateral abductor paralysis. The user wants me to explain the correct answer and why the others are wrong. First, I need to recall the muscles involved in abduction of the vocal cords. The main abductor is the posterior cricoarytenoid muscle, which is innervated by the recurrent laryngeal nerve (except for the cricothyroid muscle, which is innervated by the external branch of the superior laryngeal nerve). So, if there's unilateral paralysis of the abductor, the affected vocal cord can't abduct properly.

Wait, but the question is about the symptom. When one vocal cord can't abduct, during inspiration, the glottis becomes asymmetrical. Normally, during inspiration, the vocal cords are abducted, creating a larger opening. If one is paralyzed, the glottis is narrowed on the affected side, leading to inspiratory stridor. That's a high-pitched sound heard during inspiration.

Now, the options aren't provided, but the correct answer is likely to be stridor. The other options might include things like hoarseness (which is more common with adductor paralysis), dysphagia, or maybe something else. Let me think about why each wrong option is incorrect. For example, hoarseness is due to adductor issues because the vocal cords can't come together properly for phonation. If it's abductor paralysis, the problem is with abduction, so during inspiration, the airway is compromised, leading to stridor. Also, during speech, the unaffected cord might compensate, so maybe hoarseness isn't the main issue here. So, the key symptom is inspiratory stridor.

Clinical pearl: Remember that unilateral abductor paralysis causes inspiratory stridor, while bilateral adductor paralysis causes expiratory stridor. Also, the posterior cricoarytenoid is the only abductor, so any lesion affecting its nerve (recurrent laryngeal) on one side leads to this condition. The external branch of the superior laryngeal nerve is for the cricothyroid, which is an adductor, so that's not involved here.

So the correct answer is stridor. The other options would be incorrect because they don't relate to the primary dysfunction of abduction. Let me structure all this into the required sections with the proper formatting.

**Core Concept** Unilateral abductor paralysis results from damage to the posterior cricoarytenoid muscle, the sole abductor of the vocal cords, typically due to injury of the recurrent laryngeal nerve. This leads to impaired abduction of the affected vocal cord, narrowing the glottis during inspiration and causing airway obstruction.

**Why the Correct Answer is Right** The hallmark symptom is **inspiratory stridor**, a high-pitched, turbulent airflow sound caused by glottic narrowing during inspiration. The paralyzed vocal cord fails to abduct, creating an asymmetrical glottis that restricts airflow. During speech, the unaffected cord may partially compensate, but inspiration remains compromised, especially in supine or recumbent positions.

**Why Each Wrong Option is Incorrect**
**Option A:** Hoarseness is caused by adductor paralysis (e.g., posterior cricoarytenoid dysfunction affects abduction, not adduction for phonation).
**Option B:** Expiratory stridor suggests bilateral adductor paralysis (e.g

✓ Correct Answer: B. Transient hoarseness