How does clear cutting compare with selective cutting, and why is selective cutting considered more sustainable than clear cutting?

Explanation:

Clear cutting can be define as the removal of entire vegetation cover or large forests from a region. But in selective cutting some unwanted trees, bushes, shrubs are cut so as to increase the area for the growth of trees which are of value. Selective cutting is more sustainable than clear cutting because in clear cutting the chances of loss of diversity of plant species is more. Also some species native to a region may get extinct by clear cutting. Hence, selective cutting is more sustainable.

c. earths continental crust is thicker than its lithosphere.

because, the lithosphere is the outermost layer of the earth/ 100 km thick and is defined by its machanical properties.the lithosphere contains oceanic and continental crust that varies in age and thickness across locations and geologic time. the lithosphere is the coolest layer of the earth in terms of temperature. the term lithosphere should not be confused with the use of "geosphere" which is used to indicate all of earth systems, including the atmosphere, hydrosphere   and biosphere. the surface of the earth can be divided into the continental crust and the oceanic crust.   the continental crust is made mostly of granite while the oceanic crust is made of basalt. the average thickness of the continental crust is 25 miles and the average thickness of the oceanic crust is 5 miles.   three types of rock, igneous, sedimentary, and metamorphic, make up the surface of the earth. that's why 3 option is preferable.