International Women's Day is observed on

The correct answer is B, 22 March. The United Nations observes this day to draw attention to fresh water and the management of water resources, and in India the same date is also kept as Bihar Diwas, which makes it doubly useful for examinations.

Option A, 3 March, is World Wildlife Day, which marks the signing of the international convention on trade in endangered species. Option C, 22 April, is Earth Day, first held in 1970; the matching day of the month is exactly why it is placed here. Option D, 5 June, is World Environment Day, the best known environmental observance of the year but one that falls outside March and April altogether. Keep the order in mind: wildlife on 3 March, water on 22 March, the earth on 22 April and the environment on 5 June.

The correct answer is B, the coming into being of the World Health Organization in 1948. The constitution of the organisation took effect on 7 April 1948, and that date was chosen for the annual observance, which has been held since 1950 with a different subject each year.

Option A, the founding of the Red Cross, is marked instead by World Red Cross and Red Crescent Day on 8 May, the birth anniversary of Henry Dunant. Option C, the discovery of penicillin by Alexander Fleming, is a landmark in medicine but has no international day attached to it. Option D, the eradication of smallpox, was declared in 1980 and is commemorated in the history of the World Health Organization rather than by a separate day. Attach the year 1948 to the date and this question cannot go wrong.

The correct answer is B, 23 March. The three revolutionaries were hanged in Lahore jail on 23 March 1931 in connection with the Lahore conspiracy case, and the day is observed in their memory across the country.

Option A, 30 January, is also called Martyrs' Day, but it marks the assassination of Mahatma Gandhi in 1948, which is why the names in the question matter more than the label. Option C, 13 April, is the anniversary of the Jallianwala Bagh massacre of 1919 at Amritsar, another day of mourning in the same season. Option D, 8 August, is associated with the launch of the Quit India Movement in 1942. Read the names given in the stem: three revolutionaries point to 23 March, and Gandhi to 30 January.

The correct answer is A, 3 March. The United Nations chose this date because the international convention on trade in endangered species of wild fauna and flora was signed on 3 March, and the day is used to draw attention to wild animals and plants and to the trade that threatens them.

Option B, 20 March, carries two other observances, the International Day of Happiness and World Sparrow Day, the second of which is about a bird and therefore tempting here. Option C, 21 March, is the International Day of Forests and also World Poetry Day. Option D, 5 April, is National Maritime Day in India and has nothing to do with wildlife. March is crowded with environment related days, so learn them in sequence: wildlife on the third, sparrows on the twentieth, forests on the twenty-first and water on the twenty-second.

The correct answer is B, Robert Koch announced the discovery of the bacterium causing tuberculosis. He presented his finding to an audience of physicians in Berlin on 24 March 1882, and identifying the organism opened the way to diagnosis and eventually to treatment of a disease that was then a leading cause of death.

Option A, the founding of the World Health Organization, belongs to 7 April 1948 and is the reason for World Health Day, a different date in this same chapter. Option C, the first vaccination against tuberculosis, came decades after Koch's announcement and has no day named for it. Option D, the opening of a sanatorium, is not the basis of any international observance. The safe pair to remember is Koch on 24 March and the World Health Organization on 7 April.