Two weeks after conception, the developing fertilized egg is called a(n)

Embryo

Explanation:

The embryonic stage starts at the beginning of third week. Before this, the stage of  fertilized egg is known as blastocyst. Once the embryonic stage is reached, the cell of blastocyst become distinct and starts dividing to form human being. Thus, after the 15th day of development the growing cell mass is referred to as embryo.  The embryonic stage continues till the 8th week. By the start of 9th week , the growing cell mass converts into a fetus and this stage continues till the birth of child.

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.

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.