Explanation:

- Option 1, 26 June: This is not related to National Voters Day but it is known as the International Day Against Drug Abuse and Illicit Trafficking.

- Option 2, 25 January: National Voters Day is observed on this date. It was established by the Election Commission of India to encourage more young voters to participate in elections. This day marks the foundation day of the Election Commission of India.

- Option 3, 6 May: This date does not correspond to any significant event related to voter recognition in India.

- Option 4, 15 August: This is celebrated as India's Independence Day and is unrelated to National Voters Day.