Why Correct: Whales are marine mammals that breathe atmospheric air using lungs, surfacing regularly through blowholes evolved from nostrils.
Distractor Analysis: Integuments refer to skin and cannot serve as primary respiratory organs in whales. Gills are respiratory structures of fish and aquatic invertebrates, not mammals. Trachea is the windpipe that conducts air to lungs but not the main gas exchange site.
Takeaway: Cetacean lungs feature reinforced airways and high myoglobin concentrations allowing prolonged dives, with sperm whales capable of 90-minute breath-holds.