Explanation:

- The growing voice box in boys is commonly referred to as the Adam's apple.

- ? Correct Answer: Option 4 - Adam's apple

- The Adam's apple is the visible protrusion in the throat that appears during puberty due to the growth of the larynx.

- Option 1: Bronchi - These are the passages in the lungs, not related to the throat’s visible protrusion.

- Option 2: Thyroid cartilage - This is part of the larynx, covering and protecting it, and is involved in forming the Adam's apple, but it is not the common term for the protrusion.

- Option 3: Trachea - Known as the windpipe, this tube connects the throat to the lungs and isn’t the protrusion seen in the throat.