Does the temperature increase or decrease with altitude in the mesosphere

Temperature decreases with altitude in the mesosphere

Explanation:

Mesosphere refers to the layer in the atmosphere that lies above the stratosphere and below the layer of the thermosphere. It ranges from a height of about 50 to 80 km above the ground surface. The air in this region is very thin that does not have the ability to capture the incoming solar radiation, so the temperature in this layer decrease with the increasing altitude. The mesopause is located at the top of this layer and this forms the coldest part.

it is the second option.