A. World Cancer Day
B. World NGO Day
C. International Mother Language Day
D. World Thinking Day

Background about International Mother Language Day

International Mother Language Day is observed every year on 21 February to promote linguistic and cultural diversity and encourage multilingual education. The day was proclaimed by UNESCO in 1999 and has been observed globally since 2000.

It commemorates the 1952 Bengali Language Movement in the then East Pakistan (now Bangladesh), during which students sacrificed their lives while demanding recognition of Bangla (Bengali) as an official language.