Double-Decked Bridges feature two levels of deck.

• A. Timber Deck
• B. Precast Concrete Deck
• C. Corrugated Steel Deck
• D. Double-Decked Bridges

Answer: (D)

The main idea here is recognizing when a bridge is described as having two levels, meaning two road surfaces stacked one above the other. A bridge described as double-decked literally carries two decks, so it’s capable of handling traffic on two separate levels or directions without widening the structure horizontally.

That makes the option describing two levels the best choice, because it directly conveys the structural feature of having two decks. The other options specify the deck’s material or construction method—timber, precast concrete, or corrugated steel deck—which tell you about what the deck is made of or how it’s built, not about there being two levels. So they don’t indicate the two-tier layout that defines a double-decked bridge.