The is the coldest layer of the atmosphere.
a. troposphere
b. stratosphere
c. mesosphere
d. thermosphere

Troposphere, stratosphere, mesosphere and thermosphere are the four layers of the atmosphere

The mesosphere is the coldest layer of the atmosphere. Correct C

The emsosphere extends upward to a height of about 85 km (53 miles) above our planet. This layer is characterized with too thin air to breath and air pressure at the bottom of the layer which is well below 1% of the pressure at sea level.