Longest day/night is experienced during a year in the
- Tropics of Cancer / Capricorn
- Arctic / Antarctic Circle
The polar night occurs when the night lasts for more than 24 hours. The opposite phenomenon, the polar day, or midnight sun, occurs when the Sun stays above the horizon for more than 24 hours. It is day in the Arctic Circle and it is night in the Antarctic Circle.
Around the summer solstice (approximately 21 June in the Northern Hemisphere and 22 December in the Southern Hemisphere) the sun is visible for the full 24 hours.
The correct option is D.