The layer of atmosphere having lowest temperature is

The correct answer is Mesosphere.
🔑Key Points: Mesosphere –
-It extends above the stratosphere up to a height of about 80 km.It is the coldest layer of the atmosphere.
-The mesosphere is directly above the stratosphere.
-The stratosphere and mesosphere are collectively termed as " Middle atmosphere". 
-Within the mesosphere, temperature decreases with increasing height, due to decreasing solar heating and increasing cooling by CO2 radiative emission.

🔴Additional Information:
There are a total of five atmospheric layers.These are – 
-Troposphere
-Stratosphere
-Mesosphere
-Thermosphere
-Ionosphere: the lowest part of the Thermosphere contains the ionosphere
-Exosphere