Which process is used by heterotrophs to obtain preformed organic molecules from the environment?
a) ingestion
b) egestion
c) dehydration synthesis
d) mechanical digestion

The correct answer is A) ingestion

Explanation:

Heterotrophs are organisms that depend on other organisms to get nutrition because they can not make their food. The process by which they take nutrition is called injection.

During ingestion, they consume the performed organic molecule. Mouth is the organ that helps in ingestion of the food. Then the food is digested in the body of the heterotrophs by the action of different enzymes.  

For example, humans are heterotrophs that do ingestion of food from its mouth and then the food is digested by different hydrolytic enzymes. So the correct answer is A.

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.