Adult male humans generally have deeper voices than do adult female humans, which is the direct result of higher levels of testosterone causing growth of the larynx. If the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females and increasing larynx size in adult males, then .a. sexual dimorphism was developing over time in these speciesb. intrasexual selection seems to have occurredc. stabilizing selection was occurring in these species concerning larynx sized. selection was acting more directly upon genotype than upon phenotype

a. sexual dimorphism was developing over time in these species

Explanation:

Sexual dimorphism is an evolutionary change that occurs over time in species, which could be as a result of sexual selection which makes both sex of a species develop a systematic difference in form, which can manifest in terms of body size, color, secondary sex characteristics, and size of some structures such as larynx size which accounts for deeper voices in males in relation to levels of testosterone. This is later passed across from generation to generation over time.

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides