Introduction:
In this question, we are asked to identify the cheapest and oldest mode of transportation among the options provided: water transport, air transport, land transport, and special transport. The correct answer is option 'A', which refers to water transport. Let's delve into the details and understand why water transport is the cheapest and oldest mode of transportation.

Water Transport:
Water transport refers to the movement of goods and passengers through waterways such as rivers, canals, lakes, and oceans. It is considered the cheapest and oldest mode of transportation due to several reasons.

1. Cost-effective:
- Water transport is relatively inexpensive compared to other modes of transportation. It requires less infrastructure development and maintenance cost.
- The cost of building and maintaining water transport vessels, such as boats, ships, and barges, is lower than constructing and maintaining airports, roads, and railways.

2. Fuel efficiency:
- Water transport is highly fuel-efficient, especially when compared to air transport. Ships and boats can carry a large number of goods and passengers using relatively less fuel.
- This fuel efficiency helps in reducing transportation costs and makes water transport an economical choice.

3. Accessibility:
- Water transport provides access to remote areas that are not easily reachable by other modes of transportation.
- It connects landlocked countries or regions to the rest of the world, facilitating trade and economic growth.

4. Oldest mode of transportation:
- Water transport has been used for centuries, starting with the use of simple rafts and canoes. It played a crucial role in the development of early civilizations by enabling trade and exploration.
- Ancient civilizations like the Egyptians, Greeks, and Romans extensively used water transport for trade and military purposes.

Conclusion:
In conclusion, water transport is the cheapest and oldest mode of transportation among the options provided. Its cost-effectiveness, fuel efficiency, accessibility, and historical significance make it an important mode of transportation even in modern times.

Water Transport is the oldest and cheapest mode of transport.