The correct answer is option 1, which states that statements 1 and 2 are correct. Let`s examine each statement:

1. The first statement is correct. The Hastings Plan of 1772 aimed to establish civil and criminal courts in each district. This was done to bring about a more efficient and accessible justice system.

2. The second statement is also correct. The judges in these courts were assisted by native assessors who had knowledge of Hindu and Islamic laws. This was important in ensuring cultural sensitivity and understanding of the diverse legal traditions in India.

3. The third statement is incorrect. The Sadar Diwani Adalat, established under the Hastings Plan, was primarily focused on dealing with revenue matters and had jurisdiction over disputes beyond a certain value. It was not specifically meant for settling mercantile cases exceeding 10,000 rupees.

4. The fourth statement is not mentioned in the question and therefore cannot be verified.

In conclusion, option 1 is correct as it accurately identifies the correct statements about the Hastings Plan of 1772.