The correct answer is option 3 - Off-shore Bombay High. Currently, the Off-shore Bombay High region is the largest producer of crude petroleum in India. This region is located off the coast of Maharashtra in the Arabian Sea. It is known for its vast reserves of oil and gas, and has been a major contributor to India`s domestic oil production for several decades.

Option 1 - Assam: While Assam has historically been a significant producer of crude petroleum in India, its production has declined in recent years.

Option 2 - Gujarat: Gujarat is also an important oil-producing state in India, but it does not produce as much crude petroleum as Off-shore Bombay High.

Option 4 - Coastal Tamil Nadu: Coastal Tamil Nadu does not have significant crude petroleum reserves, and therefore, does not produce a substantial amount of crude petroleum in India.

Therefore, the Off-shore Bombay High region currently produces the highest amount of crude petroleum in India.