Why do some organisms reproduce asexually

Some organism reproduce by asexual reproduction because it does not requires much energy and is very convenient.

This type of reproduction does not requires two parent. They do not involve the fusion of male and female gamete.

The offspring produced by this process are same and it does not requires much time to produce offspring.

There is no variation in the offspring and the stability of organism produced by asexual reproduction is less as compared to that of sexual.

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.