The correct answer is: a) National Highways.
National Highways are the primary mode of road transport in Punjab. They are the major roads that connect the state to other parts of India. National Highways are well-maintained and have good road conditions. They are also well-connected to other modes of transport, such as railways and airports.
State Highways are also important roads in Punjab. They connect the major cities and towns of the state. State Highways are not as well-maintained as National Highways, but they are still a good option for road travel.
Local roads are the most common type of road in Punjab. They connect villages and towns to each other. Local roads are not as well-maintained as National Highways or State Highways, but they are still a good option for local travel.
Expressways are not as common in Punjab as they are in other parts of India. They are high-speed roads that connect major cities. Expressways are a good option for long-distance travel.
In conclusion, the primary mode of road transport in Punjab is National Highways. They are the major roads that connect the state to other parts of India. National Highways are well-maintained and have good road conditions. They are also well-connected to other modes of transport, such as railways and airports.