The correct answer to this question is option 2: U.S.A. The phrase "An indestructible union of indestructible states" refers to the federation of the United States of America. This phrase reflects the idea that the states within the United States are united in a strong and unbreakable union.

Option 1: India is not the correct answer because while India is a federation with individual states, it is not commonly described using the phrase "An indestructible union of indestructible states."

Option 3: Canada is also not the correct answer as it is not commonly described with this phrase. Although Canada is a federation with provinces, it does not use the same descriptive expression as the United States.

Option 4: Australia is also not the correct answer. While Australia is a federation with states, it is generally not described in this specific way.

To summarize, the correct answer to the question is option 2: U.S.A. as it is commonly described as "An indestructible union of indestructible states."