World Blood Donor Day, observed on 14 June, marks the birth anniversary of the scientist who discovered

The correct answer is B, 3 May. The day is kept to remind governments of their duty towards freedom of expression and to mark the risks journalists take in their work, and it is the first of the international observances in the month.

Option A, 1 May, is International Labour Day, and in India it is also the foundation day of Maharashtra and Gujarat, both created on that date in 1960. Option C, 8 May, is World Red Cross and Red Crescent Day, the birth anniversary of Henry Dunant, and is also observed as World Thalassaemia Day. Option D, 17 May, is World Telecommunication and Information Society Day, which marks the founding of the International Telecommunication Union in 1865. All four dates fall in the first half of May, which is exactly why the paper places them together, so learn the four as a block.

The correct answer is B, Florence Nightingale, who was born on 12 May 1820. Her work with wounded soldiers in the Crimean War and the training school she founded afterwards turned nursing into a trained profession, and the day carries her name in every account of it.

Option A, Mother Teresa, is remembered on other dates and is the name candidates reach for when a question joins nursing with service. Option C, Henry Dunant, founded the Red Cross movement and received the first Nobel Peace Prize; his birthday, 8 May, is World Red Cross and Red Crescent Day. Option D, Karl Landsteiner, discovered the ABO blood groups, and his birthday, 14 June, is World Blood Donor Day. Three of these four names anchor a day in May or June, so learn the set together: 8 May Dunant, 12 May Nightingale, 14 June Landsteiner.

The correct answer is B, conducted nuclear tests at Pokhran. On 11 May 1998 India carried out nuclear tests at Pokhran in Rajasthan, and the same day brought the first test flight of the indigenous Hansa aircraft and a successful test of the Trishul missile. The day was declared soon afterwards to honour Indian scientists and engineers.

Option A is wrong because India's first satellite, Aryabhata, was launched in 1975 and has no connection with this date. Option C refers to work on indigenous supercomputing from the early 1990s, again unrelated to 11 May. Option D points to the start of nuclear power generation in the country in the late 1960s, which is a different milestone altogether. Keep the three Indian days of these two months apart by their reasons: 11 May for technology, 21 May for anti-terrorism and 29 June for statistics.

The correct answer is A, Henry Dunant, the Swiss businessman whose account of the wounded left on a battlefield led to the founding of the Red Cross movement and to the first Geneva Convention. He shared the first Nobel Peace Prize, and the movement observes his birthday as its day.

Option B, Florence Nightingale, is honoured on 12 May as International Nurses Day, and the two observances lie four days apart, which is what the question is testing. Option C, Louis Pasteur, developed vaccines and the process of pasteurisation, but no day in this pair of months marks his birth. Option D, Alexander Fleming, discovered penicillin and again has no observance in May or June. Note that 8 May is also World Thalassaemia Day, so a paper may offer the same date for two different answers.

The correct answer is C, 31 May. The day closes the month and is meant to draw attention to the harm caused by tobacco in every form and to the policies that reduce its use. Being the last day of the month makes it one of the easiest dates in the chapter to fix.

Option A, 21 May, is Anti-Terrorism Day in India, kept on the anniversary of the assassination of Rajiv Gandhi in 1991. Option B, 29 May, is Everest Day, marking the first ascent by Edmund Hillary and Tenzing Norgay in 1953, and is also the International Day of United Nations Peacekeepers. Option D, 1 June, is World Milk Day, and it is the neighbouring date that most often draws a wrong answer here. Learning the end of May and the start of June as one short run protects you from all three distractors.