Correct Option: D

Twin cities are a special case of two cities or urban centres that are founded in close geographic proximity and then grow into each other over time. Cities twinned geographically do not necessarily match demographically, economically, or politically. Examples of twin cities in India are: Ahmedabad and Gandhinagar, Gujarat, are looked upon as merging into a new twin city in-the-process; Kolkata and Howrah, West Bengal; Hyderabad and Secunderabad, Andhra Pradesh; Siliguri and Jalpaiguri, West Bengal; Durgapur and Asansol; etc.