Clarity why a diagram of evolution looks more like a bush than a straight line

The reason why an evolutionary diagram looks more like a bush than a straight line is the development of new species.

To be more clear - initially we can have one species, and that species will over time start to live in multiple different environments. As the species starts to adapt to the new environment, its appearance and genetics are gradually changing in order for it to have more advantageous traits to survive in the environment. As the time passes, the changes that will emerge in some members will create a new species, and that process will constantly go on, until extinction that is. So we have one species that is an ancestor of multiple new species, thus the family tree, or rather evolutionary diagram, starts to branch out, and as the time passes, it will branch out more and more and take a bush-like looks.

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.