Identify the atmospheric layer from the given features A and B: A. Meteoroids…

Concept: Earth's atmosphere is divided into layers based on temperature behaviour with altitude. The mesosphere (roughly 50-85 km above the surface) is the layer where temperature falls sharply with increasing height, reaching the coldest point in the whole atmosphere at its top, and it is also the layer where friction with air molecules burns up most meteoroids entering from space before they can reach the ground.

Application: Feature A (meteoroids burning up on entry) is the defining, distinguishing signature of the mesosphere among the offered layers - this is the layer dense enough, at high enough altitude, to cause frictional heating that disintegrates incoming space debris. Feature B (temperature falling as height increases) is also true of the mesosphere, so both stated features point to the same single layer.

Cross-check: Temperature does fall with height in the troposphere too, but the troposphere does not burn up meteoroids - that happens far higher up. Ruling the troposphere out by feature A alone, and confirming feature B independently for the remaining candidate, leaves only one layer consistent with BOTH clues together.

In the stratosphere and thermosphere, by contrast, temperature rises with height (due to ozone absorption in the stratosphere and solar radiation absorption in the thermosphere) - the opposite of feature B - so neither fits.