Which is the world’s oldest operating oil refinery?

A. Bahamas
B. Digboi
C. Texas
D. Basra

Digboi is known as the Oil City of Assam where the first oil well in Asia was drilled. The first refinery was started here as early as 1901. Digboi has the oldest oil well in operation. World’s oldest oil refinery in Assam turns 100. The world’s oldest operating oil refinery in the northeastern state of Assam celebrated its centenary with a pledge to produce high quality diesel, wax and other petrochemicals.