单选题 The author feels that a comparison of liquid and solid-fuel rockets shows that ______.

【正确答案】 C
【答案解析】文中提到一些外行可能会问，相较而言liquid and solid-fuel rockets哪个更好，作者对此问题的看法是The question is meaningless，接着在文中分别阐述了两种类型火箭各自的优缺点，可以判断选项C符合。