Explanation:

- Elasticity in transportation indicates how demand responds to price changes.

- Option 2: Rail

- Rail transportation typically has moderate elasticity, as it's essential for passengers and freight services.

- Option 1 and 3: Air and Road

- Generally, road transport is considered to have higher price elasticity of demand than air travel. This means that road travel demand is more sensitive to changes in price (like fuel costs or tolls) than air travel demand, leading to larger changes in road travel volumes for the same price changes.

- Option 4: Water

- Water transport generally has low elasticity, focused on bulk goods with few alternatives.