Consider the following statements about ‘Rules of Origin’ :

1. Rules of Origin are the criteria needed to determine the national source of a product.

2. Rules of Origin help the custom agencies to know what regulations and fees apply to a given product.

3. These are used for the purpose of trade statistics.

4. Their importance is derived from the fact that duties and restrictions in several cases depend upon the sources of imports.

Which of the above statements are correct?