Correct Answer:
Option D - A red-letter day - A memorably important or happy occasion. It signifies a special or memorable day such as a holiday, birthday, anniversary or any historical date. Hence, option (d) is correct.
D. A red-letter day - A memorably important or happy occasion. It signifies a special or memorable day such as a holiday, birthday, anniversary or any historical date. Hence, option (d) is correct.