Task: Class Definition Understanding (ontology: Sciences/Biology)

Which of the following definitions best describes 'D-phenylalanine'?

A. The D-enantiomer of phenylalanine.
B. An optically active form of tyrosine having D-configuration.
C. The L-enantiomer of the concept.
D. A D-tyrosine derivative that is D-tyrosine phosphorylated at the phenolic hydroxy group.

Answer: The D-enantiomer of phenylalanine.