Explanation:

- Option 1: 12 March 2020

- Incorrect. The provisions were not enforced on this date.

- Option 2: 23 June 2020

- Incorrect. The Consumer Protection Act, 2019 was not operational from this date.

- Option 3: 30 April 2020

- Incorrect. This date does not mark the commencement of the Act’s provisions.

- Option 4: 20 July 2020

- Correct. This is when the main provisions of the Consumer Protection Act, 2019 came into force, including provisions related to consumer rights and redressal mechanisms.