Only male frogs produce the characteristic croaking sound because of which of the following special features related to their voice production?

Introduction / Context:
The loud croaking sound heard near ponds and wetlands, especially during the rainy season, is typically produced by male frogs. This sound plays an important role in communication and mating behaviour. Female frogs are usually much quieter. The question asks you to identify the specific anatomical and functional reason why only male frogs produce such prominent croaking sounds.

Given Data / Assumptions:

• We are comparing male and female frogs with respect to sound production.
• The options mention the larynx, vocal cords, and a sound box (vocal sacs).
• We assume normal anatomy of common frog species used in school biology.
• Only one option correctly explains the special structure that allows males to produce loud mating calls.

Concept / Approach:
Both male and female frogs possess a larynx, and both can have vocal cords. However, male frogs typically have well developed vocal sacs, thin walled inflatable structures in the throat region that act as resonating chambers or sound boxes. When a male frog calls, air is passed over the vocal cords and then into the vocal sacs, which expand and amplify the sound. Female frogs either lack such developed vocal sacs or have them much reduced, so they do not produce the same loud croaking calls. Therefore, the key reason involves the presence of an efficient sound amplifying apparatus in males.

Step-by-Step Solution:
Step 1: Recall that croaking is mainly a mating call produced by male frogs to attract females and mark territory.Step 2: Note that both sexes have basic laryngeal structures, so total absence of a larynx in females is incorrect.Step 3: Understand that male frogs possess vocal sacs which can balloon out when they call, acting as resonating chambers.Step 4: These vocal sacs allow male frogs to magnify and project their voice over long distances.Step 5: Hence, the correct explanation is that male frogs can amplify their voice using a sound box or vocal sac system, while females generally cannot.

Verification / Alternative check:
Dissections and diagrams in zoology textbooks clearly show male frogs with distinct vocal sacs, whereas females either lack these sacs or have them much less developed. Behavioural studies also confirm that the loud advertisement calls used in breeding seasons are produced by males. This evidence supports the idea that sound amplification via vocal sacs is the main reason only males create the classic croaking sound heard in the environment.

Why Other Options Are Wrong:
Female frogs having no larynx is anatomically incorrect; both sexes have a larynx.The claim that females have a larynx but no vocal cords is oversimplified and not accurate for typical frog species.Male frogs do not possess three pairs of vocal cords; the number of vocal cords is not the main reason for loud croaking.The idea that females are silent only because their vocal cords are smaller ignores the crucial role of vocal sacs in sound amplification.

Common Pitfalls:
Students sometimes assume that females completely lack voice producing organs, which is not true. Another mistake is focusing only on vocal cords without considering the resonating structures that amplify sound. To avoid confusion, remember that the most important difference is the presence of well developed vocal sacs in male frogs, which act as sound boxes and allow them to produce loud croaking calls.

Final Answer:
The correct answer is: Male frogs can greatly magnify their voice using inflatable vocal sacs (sound box).