单项选择题

下列反应中形成具有启动功能的起始复合物的步骤是()

A.30S+mRNA→3oS·mRNA
B.30S·mRNA+fMet-tRNA+GTP→30S·mRNA·fMet-tRNA·GTP
C.30S·mRNA·fMet-tRNA·GTP+50S→70S·mRNA·fMet-tRNA+GDP+Pi
D.tRNA+Met→Met-tRNA