38. A pure sample of (S)-phenylalanine has a specific rotation of +70o . A mixture of the two enantiomers of phenylalanine gives a specific rotation of -7.0o . What are the percentages of the S and R enantiomers in the mixture? (A) 75 % S, 25 % R (B) 65 % S, 35 % R (C) 55 % S, 45 % R (D) 45 % S, 55 % R (E) 35 % S, 65 % R