The correct option is 3, which means statements 1 and 3 are correct, while statement 2 is incorrect. Let`s dissect each statement to understand why.

Statement 1: "He was a big bore rifle shooter who won two gold medals during the first Commonwealth Championship."

This statement is correct. It highlights Subdar Major Fateh Singh`s achievement as a big bore rifle shooter and mentions that he won two gold medals during the first Commonwealth Championship. This showcases his skill and success in shooting.

Statement 2: "He retired from Bihar Regiment before joining Defence Service Corps."

This statement is incorrect. It suggests that Subdar Major Fateh Singh retired from the Bihar Regiment before joining the Defence Service Corps. However, there is no information provided in the question or the context about his retirement or joining any particular regiments or organizations.

Statement 3: "He was killed during the terror attack at Pathankot Air Force Base."

This statement is correct. It states that Subdar Major Fateh Singh was killed during a terror attack at the Pathankot Air Force Base. This highlights a tragic event in his life where he lost his life while serving at the base.

In conclusion, option 3 is the correct answer, as statements 1 and 3 are true