Concept:Pipelines provide a fixed, continuous transport system best suited for moving fluids over long distances.
Explanation:Liquids such as crude oil and gases such as natural gas require safe and uninterrupted movement within a country.
Tankers need repeated loading and unloading, which increases time and handling risks.
Aircraft are very costly and cannot carry large volumes of liquid or gas economically.
Pipelines allow a steady and direct flow from the source to the destination.
They reduce losses, lower operating costs, and avoid transit delays.
Hence, pipelines are the most suitable means for long-distance transport of liquid and gas.
Answer:C. pipeline