What is the main purpose of scientific models? a. the main purpose of models is to have a physical object to which to refer. b. the main purpose of models is to represent observations. c. the main purpose of models is to study systems that no longer exist. d. the main purpose of models is to gain a better understanding of the world

The scientific model is a representation of an object or event.Scientific models make it easier to understand things that might be too difficult to observe directly.

The main purpose of models is to gain a better understanding of the world. Correct D

d. The main purpose of models is to gain a better understanding of the world.

Explanation:

Scientific models are the demonstrating artificial models which are designed in order to represent various natural phenomena occurring on earth and to describe the various physical features of the earth. They help in understanding, defining, quantifying, visualizing and simulating various natural processes and physical features of the world.

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.