The correct option is option 3, which states that the All India Census was first attempted in 1872 and has been regularly undertaken since 1881. This means that option 1, which states that the All India Census was first attempted in 1872 only, is incorrect.

Option 2 states that the All India Census has always been undertaken as a five-year exercise, but this is not mentioned in the question and cannot be determined from the information provided. Therefore, option 2 is also incorrect.

Option 4 includes all three options, which are:

1. The All India Census was first attempted in 1872.

2. The All India Census has been regularly undertaken since 1881.

3. The All India Census is always undertaken as a five-year exercise.

Since option 4 includes the correct options, it would be considered correct if option 3 was not available. However, option 3 explicitly states the correct options without including the additional information in option 4. Therefore, option 3 is the best answer choice.