The correct answer is: b) Lower than daytime temperatures.
Nighttime temperatures in Tamil Nadu generally tend to be lower than daytime temperatures. This is because the sun’s heat is not directly hitting the Earth’s surface at night. The Earth’s surface cools down, and the air temperature drops as well.
Option a) is incorrect because the sun’s heat is not directly hitting the Earth’s surface at night, so the Earth’s surface does not heat up as much as it does during the day. This means that the air temperature is also lower at night.
Option c) is incorrect because the Earth’s surface cools down at night, and the air temperature drops as well. This means that the air temperature is not similar to the daytime temperature.
Option d) is incorrect because nighttime temperatures in Tamil Nadu generally tend to be lower than daytime temperatures. This is not unpredictable.