Concept:The atmosphere has vertical layers, and the temperature trend in each layer depends on its composition and energy absorption.Explanation:In the troposphere, temperature steadily decreases with altitude.In the stratosphere, temperature increases with altitude because the ozone layer absorbs ultraviolet radiation from the Sun.The ionosphere and exosphere do not show the same consistent warming trend with altitude as the stratosphere does.Hence, the layer with increasing temperature with altitude is the stratosphere.Answer:C. Stratosphere