Why is the bottom of the troposphere warmer than its top portion?

The reason for this temperature fluctuation is that ozone absorbs the uvb radiation in the lower atmosphere. Higher in the atmosphere, however, normal diatomic oxygen absorbs the uvc radiation. Once it is absorbed, it is reradiated at different wavelengths, thereby warming the stratosphere

the temperature generally decreases with altitude. The reason is that the troposphere's gases absorb very little of the incoming solar radiation. Instead, the ground absorbs this radiation and then heats the tropospheric air by conduction and convection. Since this heating is most effective near the ground, the temperature in the troposphere gradually decreases with increasing altitude until the tropopause is reached.

In the troposphere, the temperature generally decreases with altitude. The reason is that the troposphere's gases absorb very little of the incoming solar radiation. Instead, the ground absorbs this radiation and then heats the tropospheric air by conduction and convection.

Why you put last one a? i think is b.