What bridge deck material is desirable for its resistance to decaying agents?

• A. Aluminum
• B. Concrete
• C. Timber
• D. Steel

Answer: (C)

The key idea is resistance to decay-causing agents like fungi, moisture, and insects. Timber can be made highly resistant to decay through proper preservative treatment, which protects the wood from rot and insect attack over time. This makes treated timber a practical choice for deck components in environments where moisture exposure is common, because its life can be extended with protective chemicals and regular maintenance. In contrast, metals are prone to corrosion and deterioration in moist conditions, and concrete can suffer from chemical or freeze–thaw damage, so without treatment timber offers a reliable edge against decay when preserved correctly.