In a certain breed of dog, the alleles B and b determine black and brown coats respectively. However, the allele Q of a gene on a separate chromosome is epistatic to the B and b color alleles resulting in a gray coat (q has no effect on color). If animals of genotype B/b ; Q/q are intercrossed, what phenotypic ratio is expected in the progeny

12 gray , 3 black, 1 brown

Explanation:

If Q allele of a gene on a separate chromosomes is epistatic to the B (black) and b (brown) color alleles, in cross between two animals with genotypes BbQq produces 12 gray coat color, 3 black coat color and 1 brown coat color animals.

                                        BbQq      x      BbQq

                                   Gray coat        Gray coat

                   BQ                  Bq                 bQ                 bq

   BQ    BBQQ(gray)  BBQq(gray)   BbQQ(gray)   BbQq(gray)

   Bq     BBQq(gray)   BBqq(Black)  BbQq(gray)   Bbqq(Black)

   bQ     BbQQ(gray)  BbQq(gray)   bbQQ(gray)   bbQq(gray)

   bq     BbQq(Gray)   Bbqq(Black)  bbQq(gray)    bbqq(brown)

So the phenotypic ratio is  Gray : Black : Brown

                                        =      12  :      3   :      1

but there is no

i guess you forgot putting it.

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.