The four major functions of hormones are _

the correct answers are -

a) homeostasis

b) immunity

c) reproduction

d) growth and development

reason -

the endocrine system (produces and secretes hormones) is a vital system as it regulates the homeostasis by regulating the cell activity in the body. the endocrine system releases relevant hormones during specific time period in the blood which are then   transported across the blood , this not only maintains the chemical physical balance in our body but also regulate the vital functions of body such as growth, reproduction, and immunity  

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.