Tom looks out his window. Which observation includes a biotic factor of the ecosystem he is in. A. It is raining.
B. There are worms on his sidewalk.
C. The water in his pond is higher than usual.
D. The clouds are darker than they had been a little earlier.

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.

economic impact of malaria is estimated to cost africa $12 billion every year. this figure factors in costs of health care, absenteeism, days lost in education, decreased productivity due to brain damage from cerebral malaria, and loss of investment and tourism.

just finished the test, the answer is d, greg is the least cost-effective because he charges the most for the project