The correct answer is option 'C' - Golden Quadrilateral (GQ)

The Golden Quadrilateral (GQ) is a network of highways in India that connects the four metro cities of Delhi, Mumbai, Kolkata, and Chennai. It is one of the largest highway projects in the country and was undertaken by the government to improve connectivity and promote economic development.

The GQ project was launched by the Atal Bihari Vajpayee-led government in 2001. It is a four-lane highway project that covers a distance of approximately 5,846 kilometers. The aim of the project was to connect the major cities of India and create a seamless road network that would facilitate the movement of goods and people across the country.

Here are some key features of the Golden Quadrilateral:

1. Connects Major Cities: The GQ connects Delhi in the north, Mumbai in the west, Kolkata in the east, and Chennai in the south. These cities are the major economic and cultural centers of the country, and the GQ provides a vital link between them.

2. Four-Lane Highways: The GQ comprises four-lane highways, which provide a smooth and efficient road network for transportation. These highways have separate lanes for different types of vehicles, such as cars, trucks, and motorcycles, which ensures safety and reduces congestion.

3. Economic Impact: The GQ has had a significant impact on the economy of India. It has facilitated the movement of goods and services across the country, reducing transportation costs and improving efficiency. The improved connectivity has also attracted investment and promoted economic development in the regions along the GQ.

4. Reduced Travel Time: The GQ has significantly reduced travel time between the four metro cities. Earlier, it used to take several days to travel between these cities, but now, it can be done in a matter of hours. This has made travel more convenient and has also boosted tourism.

5. Infrastructure Development: The construction of the GQ has led to the development of infrastructure along the highway corridor. This includes the establishment of rest areas, petrol pumps, restaurants, hotels, and other amenities. It has also created employment opportunities in the construction and maintenance of the highway.

In conclusion, the Golden Quadrilateral is the national highway that connects the four metro cities of India - Delhi, Mumbai, Kolkata, and Chennai. It has played a crucial role in improving connectivity, promoting economic development, and reducing travel time between these cities.