I think it may be this but not quite sure
Lipids are primarily hydrophobic in nature, but there are a large variety of lipids such as fatty acids, mono-, di-, and triglycerides, for example (check wikipedia for more examples).
<span>Proteins are polymers of amino acids. </span>
<span>Nucleic acids are polymers of nucleotides.</span>
Law would be the correct answer to fill in the blank. Law is correct because scientific law explains behaviors of natural phenomenons since it's based on repeated experiments.
They are called hand antiseptics.
The answer to your question would be (<span>barter)</span>