34. What two modifications are required for serotonin biosynthesis from tryptophan?
(A) hydroxylation and decarboxylation
(B) adenosylation and methylation
(C) dehydrogenation and phosphorylation
(D) hydrogenation and phosphorylation
(E) decarboxylation and hydrogenation.

題目解析本題目詢問的是從色氨酸（try...