The number of currently described species on the planet is about
17,000
150,000
1.5 million
10 million

1.5 million

Explanation:

To date, approximately 1.5 million species have been described, including animals, fungi, lichens, plants and protists. However, the actual number of species between those that are already described and those that have not yet been discovered is estimated to exceed 30 million species.

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.

bru what tyep of qus is dis