单选题 If Finn was 18 months old one year ago, how old was he, in months, x months ago?
A. x-30
B. x-12
C. 18-x
D. 24-x
E. 30-x

【正确答案】 E
【答案解析】If Finn was 18 months old one year ago, then he is now (18+12=) 30 months old. 30-x represents his age in month x months ago.