Explanation:

- Option 1: US and Russia

- The United States and Russia are pioneers in developing and operating advanced hypersonic wind tunnel test facilities.

- Both countries have extensive experience in hypersonic technology research.

- Option 2: China and South Korea

- China has made strides in hypersonic technology, but South Korea is not known for having such facilities.

- Option 3: Japan and China

- Only China has significant hypersonic developments; Japan does not have a comparable wind tunnel facility.

- Option 4: Australia and Japan

- Neither Australia nor Japan are recognized for having such advanced wind tunnel facilities.

- Option 5: None of the above

- This is incorrect as the US and Russia do have such facilities.