Choose the alternative which best expresses the meaning of the Idiom/Phrase.
26th January is a red-letter day in the history of India

Historic day

The answer is **(☀) Historic day.

The idiom "red-letter day" means a day that is especially important or memorable. It is often used to describe a day that marks a significant event in history. In this case, the 26th of January is a red-letter day in the history of India because it is the day that the Indian Constitution came into force and India became a Republic.

The other options are incorrect. (2) Blood donation day is not a red-letter day. It is a day that is dedicated to raising awareness about blood donation and encouraging people to donate blood. (3) Holiday is not a red-letter day. A holiday is a day on which people do not have to work or go to school. (4) Important day is not as specific as "historic day". An important day can be any day that is significant or memorable, but a historic day is a day that marks a significant event in history.