Which is the longest day and the shortest night in the southern hemisphere?
A. 22nd December
B. 23rd December
C. 22nd June
D. None of the above

Hint: The earth is tilted on its axis by 66.5 degrees. This way, on two specific days of the year one pole of the earth is tilted away the most from the sun. The pole near to the sun, therefore, has the longest day and the shortest night. In the other pole, the exact opposite phenomenon happens.

Complete answer:
In the southern hemisphere, 22nd December has the longest day and the shortest night. The earth is tilted on its axis by 66.5 degrees. This way, on two specific days of the year one pole of the earth is tilted away the most from the sun. The pole near to the sun, therefore, has the longest day and the shortest night. On the other pole, the exact opposite phenomenon happens. The winter solstice is also known as the hiemal solstice or the hibernal solstice. It occurs when one pole of the Earth has tilted away the most from the Sun. It happens twice every year, once in each hemisphere. On this day, the Sun is at its lowest elevation in the sky. At the poles, there is either continuous darkness or twilight during the winter solstice.
In the Northern Hemisphere, this is known as the December solstice (21st or 22nd December) and in the Southern Hemisphere, this is the June solstice (20th or 21st June).
So, the correct answer is Option A.

Note: On the day of the summer solstice in the north pole, there is the winter solstice in the south pole and vice versa. Summer solstice in the North Pole occurs on 21st June, winter solstice on 22nd of December, and the vernal and autumnal equinoxes occur on 21st of March and 23rd of September respectively.