Step 1: Understand the question.
We need the date when the National Education Policy 2020, called NEP 2020, came into effect in India.
Step 2: Recall what NEP 2020 is.
NEP 2020 is a big reform of the whole education system. It replaced the older 1986 policy and changed the school and college structure. Since it is named 2020, the date should fall in that year.
Step 3: Rule out dates that are clearly in other years.
01 January 2021 and 15 August 2021 are in 2021, so they do not fit a policy named 2020. We set them aside.
Step 4: Compare the two 2020 dates.
That leaves 29 July 2020 and 01 April 2020. The policy was approved by the Union Cabinet and announced in the second half of the year, not in April.
Step 5: Pick the exact date.
NEP 2020 was approved and came into effect on 29 July 2020. So that is the correct date.
Step 6: Match with the options.
The second option matches.
\[ \boxed{\text{29 July 2020}} \]