Explanation:

- Russia has become India's top oil supplier in October, surpassing Saudi Arabia and Iraq. Russia has increased its oil exports to India due to geopolitical shifts and competitive pricing.

- Ukraine does not have a significant oil export relationship with India, primarily due to its limited oil production capacity and current geopolitical challenges.

- Iran, though historically a significant supplier, has faced sanctions which have affected its oil exports to India.

- Nigeria is a notable oil exporter, but it has not surpassed major suppliers like Saudi Arabia, Iraq, or Russia in the Indian market recently.

- The USA exports oil but has not been a primary supplier to India compared to Middle Eastern countries or Russia.