Can someone me out with this multiple choice question?

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

answer///unconditioned stimulus;

while the heads of the phospholipid structure attract water, the tails are hydrophobic. the model shows how the hydrophilic section folds around the fluid molecules to bring them into the cell so they don’t need to pass through the hydrophobic tails.