How does crossing over break up linkage between alleles?

It involves a physical exchange of segments from homologous chromosomes. Because of crossing over, alleles originally located on the same chromosome can end up on different chromosomes and be inherited independently

stratosphere: as the altitude increases, the air temperature increases. the stratosphere has a layer of ozone, called the ozone layer. this layer absorbs most of the ultraviolet radiation from sunlight. this results in the stratosphere being warmer.

b. lithosphere, asthenosphere, mesosphere   is the answer most likely