Answer : Delhi-Mumbai-Chennai-Kolkata
Explanation: The Golden Quadrilateral (GQ) is a national highway network connecting most of the major industrial, agricultural, and cultural centers of India. It forms a quadrilateral connecting the four major metro cities of India, viz., Delhi (North), Kolkata (East), Mumbai (West), and Chennai (South).
Other cities connected by this network include Ahmedabad, Bengaluru, Balasore, Bhubaneswar, Cuttack, Durgapur, Jaipur, Kanpur, Pune, Kolhapur, Surat, Vijayawada, Ajmer, Vizag, Bodhgaya, Varanasi, Allahabad, Agra, Mathura, Dhanbad, Gandhinagar, Udaipur, and Vadodara. The main objective of these superhighways is to reduce the distance and time between the four megacities of India.