A multicellular organism typically begins as a single cell, and then many cell divisions occur to generate the cells of the adult organism. However, these cells are not identical to the original cell, and they are not identical to one another.

What is the most significant cause of cell differentiation in a multicellular organism?

A.
differences in the number of chromosomes per cell
B.
differences in the genetic code used by different cells
C.
differences in the DNA that is copied and distributed among the cells
D.
differences in gene regulation and gene expression among the cells

D

Explanation:

Difference in cell regulation and cell expression. This is embedded in chromosomes which is the blue print of the organism. The chromosomes is like the house plan when you building a house.

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.