The correct answer is option 1, which states that only statement 1 is correct. Let`s analyze each option to understand why.

Option 1: "1 only" - This means that only statement 1 is correct. If we refer to the statements provided, statement 1 states that currently three waterways have been declared as the national waterways of India. This means that there are at least three waterways that have been designated as national waterways in India.

Option 2: "2 only" - This means that only statement 2 is correct. Statement 2 states that the Sadiya-Dhubri stretch of river Brahmaputra is the longest national waterway. However, this statement has not been mentioned in the question or any other context, so we cannot determine its accuracy based on the information given.

Option 3: "Both 1 and 2" - This means that both statement 1 and statement 2 are correct. However, as explained earlier, we cannot determine the accuracy of statement 2 based on the given information.

Option 4: "Neither 1 nor 2" - This means that both statement 1 and statement 2 are incorrect. However, statement 1 has been verified to be