The rna world hypothesis proposes that when life first evolved, rna both stored genetic information and directed the synthesis of proteins. according to the hypothesis, dna evolved from rna, and then it replaced rna as the genetic storage molecule. several observations that support the rna world hypothesis are given below.
rna stores genetic information.
rna can replicate itself.
rna is structurally similar to dna.
rna synthesizes proteins.
in contrast to rna, dna is not able to directly synthesize proteins nor can it replicate itself. however, according to the hypothesis, dna was able to replace rna as the genetic storage molecule.

italy's population growth rate is almost at zero, the national statistics agency, istat, said on monday, mainly due to a dwindling birth rate.

it's not c. i took the quiz and got it wrong. so my best guess is b.

have a great day, and hope this .

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.

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.