Explanation:

- Option 1: Iraq

- As of December 2019, Iraq was indeed the largest supplier of crude oil to India. Iraq provided a significant portion of India's crude requirements, benefitting from both cost advantages and high-quality crude oil.

- Option 2: Saudi Arabia

- Saudi Arabia has traditionally been a major oil supplier to India but had been surpassed by Iraq during this period due to competitive pricing and favorable trade terms.

- Option 3: United Arab Emirates

- The UAE is also a notable supplier of crude oil to India. However, it was not the largest supplier compared to Iraq and Saudi Arabia as of December 2019.

- Option 4: Iran

- Iran was previously a significant supplier to India. However, due to U.S. sanctions, India's imports from Iran considerably reduced, making it a lesser supplier by December 2019.

Correct Answer: Option 1: Iraq