单项选择题

A.0.135-(0.135-0.09)*(5-G)/(15-5)
B.0.135-(0.135-0.09)*(G-5)/(15-5)
C.0.09-(0.09-0.06)*(15-G)/(30-15)
D.0.09-(0.09-0.06)*(G-15)/(30-15)