Hint: The largest oil field of India was discovered in 1965 which started its production in 1974. The oil operation of this field is run by India’s Oil and Natural Gas Corporation (ONGC).
Complete Answer: The Bombay high or Mumbai High, an offshore oil field was discovered by an exploration team of the Indian oil in 1964 - 67. It is located 176 kilometres north-west of Mumbai on the continental shelf off the coast of Maharashtra. It accounts for about 15 percent of India’s oil requirements and near about 38 percent of our domestic production. The Bombay High produced 110,000 barrels per day as of 2005. With the help of a specially designed platform, Sagar Samrat, the oil is obtained from a depth of over 1400 metres. The crude oil produced from this field is of very good quality as compared to the crude quality of the middle east. The is divided into two different blocks on the basis of shale barrier - Mumbai High North (MHN) and Mumbai High South (MHS).
Now let us examine the option:
Option A - The Digboi oil field is located on the rocks of the Tipam series in the northeastern state of Assam. It was set up by Assam Oil Company Ltd. in 1901 which was later acquired by the Indian Oil Corporation.
Option B - The Bombay High is the largest oil field of India and as of 2018 it produced 205,000 barrels per day.
Option C - The Ankleshwar oil field is located in the Bharuch district of Gujarat and is comparatively smaller than the Digboi oil field and Bombay High oil field.
Option D - Oil fields of the Brahmaputra valley includes Nahorkatiya, Lakhmani, Geleki dikom etc. these oil fields are quite small as compared to the other oil fields. Assam is the oldest oil producing state in India located in the Brahmaputra valley of northeastern India.
Thus, the correct answer is option (B).
Note: The oil field crude contains more paraffinic content of about 60 percent in contrast to the light Arabian crude which contains only 25 percent of paraffin. In April 2007, the ONGC approved the construction of seven pipelines with associated top-side and risers facilities.