2. which of the following statements about the inner planets is true ? ( 1point )
a. they all have rings
b. they have all abundant liquid water
c. they all have many moons
d. they are small and have rocky surfaces

the  frequency of a wave represents  the number of wavelengths that pass a specific point per second. the unit for  frequency  is hertz (hz).

happy to

pls mark as brainliest

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).