In Earth's troposphere, the lowest level of the atmosphere, temperature decreases with increasing height, but in the stratosphere, the next layer above the troposphere, temperature increases with increasing height. This happens because the stratosphere

The stratosphere contains ozone which traps solar radiation

Explanation:

Increase in temperature with increase in altitudes in the stratosphere is caused by the presence of ozone which traps solar radiation thus causing temperature to increase in the stratosphere with increase in altitude.

the wrong statement is - c. a desert had more biodiversity than a marsh.

the deserts are one of the places of the planet where there's the least biodiversity. the reasons for that are the climate and the lack of food sources, which hampers both the number of the species that can survive in it, and the number of the individuals in the species itself.

the marshes, on the other hand, are places where there's perfect conditions for lots of organisms to thrive. the temperature is moderate and nice, the amount of water and the food sources are on a high level, so there's an abundance of both plant and animal life in them.

81 is a composite number.