Final answer:
The b) vocal folds, or vocal cords, are the structures that actually produce sound by oscillating as air passes through them, and their size and tension determine the pitch of the sound.
Step-by-step explanation:
The structures that actually produce sound within the human body are the vocal folds, also commonly known as the vocal cords. These are a pair of white, membranous folds attached by muscle to the thyroid and arytenoid cartilages of the larynx on their outer edges. The inner edges of the vocal folds are free and can oscillate, which allows them to produce sound as air passes through them. The size and tension of these folds determine the pitch of the sound produced, with larger folds generally producing a deeper voice, commonly seen in males.