More than 80 percent of the world's population uses remedies to treat illness and optimize health.

Herbal

Explanation: The use of herbal medicinal products and supplements has increased over the past three decades with not less than 80% of people worldwide relying on them for some part of primary healthcare. Source-www.ncbi.nlm.nih.gov

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.