Explanation:

- Option 1: 12 March 2020

- This date is unrelated to the enforcement of the Consumer Protection Act, 2019. There were no significant events regarding this act on this day.

- Option 2: 23 June 2020

- On this date, the Indian government issued a notification bringing sections of the Consumer Protection Act, 2019 into force. However, this was not when the entire act became effective.

- Option 3: 30 April 2020

- There is no association of this date with the implementation of the Consumer Protection Act, 2019.

- Option 4: 20 July 2020

- This is when most of the provisions of the Consumer Protection Act, 2019 came into effect, marking the official enforcement of the act.