50. Refer to the figure showing structures of amino acids, which are small biological molecules found in living cells. Each amino acid has a unique side chain, shown in the boxed portion of its structural formula. Which amino acid(s) has/have hydrophobic side chains? a. Serine and asparagine b. Leucine only c. Leucine and phenylalanine d. Asparagine and leucine e. Serine, leucine, and phenylalanine .