Why do some combinations of chromosomal centric fusions cause problems in meiosis?

Because centric fusions modify the chromosome number

Explanation:

The centric fusion is a translocation that involves acrocentric chromosomes. During cell division, pairs of homologous chromosomes are aligned on the equatorial plane and subsequently they move to opposite poles in the cell.

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.