The correct answer is option 1 - "1 only".

Let`s dissect each option to understand why it is correct or incorrect:

Option 1: "1 only" - This statement suggests that "Tudh Abhyas 2014" was an India - USA military exercise. This is the correct answer.

Option 2: "2 only" - This statement claims that "Tudh Abhyas 2014" was conducted in Himachal Pradesh. However, there is no information provided in the question or context about the location of this exercise. Therefore, we cannot determine whether this statement is correct or incorrect based on the given information.

Option 3: "Both 1 and 2" - This option suggests that both statements 1 and 2 are correct. However, since we cannot verify the accuracy of statement 2, we cannot conclude that both statements are correct. Therefore, this option is incorrect.

Option 4: "Neither 1 nor 2" - This option suggests that both statements 1 and 2 are incorrect. However, as mentioned earlier, statement 1 is correct. Therefore, this option is incorrect.

In conclusion, option 1 - "1 only" is the correct answer as it accurately states that