我想你沒有錯，錯的是題目出得不科學。　　

首先要肯定的是，你選C是對的，命題者給的答案B也是對的。　　

▲as…as possible是英語中的常用結構。又如：　　

Tell him as little as possible.  盡量少告訴他。　　

Pack the case as tight as possible. 盡量把箱子裝滿。　　

I need the money as soon as possible. 我需要盡快得到這筆錢。　　

She needs to get to the hospital as soon as possible.  她需要盡快送醫院。　　

▲表示類似意思，英語也可以說as…as one can [could]。如：　　

I’ll come as soon as I can. 我將盡早來。　　

I’ll get back as quick as I can. 我要盡快回來。　　

He ran as quickly as he could. 他有好快就跑好快。　　

We drove as fast as we could to the hospital. 我們盡快開車前往醫院。　　

▲但是，能不能說 as…as one is [was] able (to) 呢？回答是肯定的。如：　　

《牛津高階英漢雙解詞典》(第四版)對run as fast as one’s legs can carry one 的解釋是：as fast as one is able 盡快地跑　　

《麥克米倫高階美語詞典》對to the best of your ability的解釋是：as well as you are able　　

《朗文當代英語辭典》(第4版) 對to your best的解釋是：performing as well or effectively as you are able to　　

《朗文當代英語辭典》(第4版) 對動詞 perfect 的解釋是：to make something as good as you are able to