18. What format of tetrahydrofolate (THF) is used for methionine biosynthesis?
(A) N⁵-methyl-THF,
(B) N⁵ N¹⁰-methylene-THF,
(C) N¹⁰-formyl-THF,
(D) N⁵-formyl-THF,
(E) N⁵N¹⁰-methenyl-THF.

1. 題目解析這道題目詢問的是在甲硫...