Even though the direct costs of malpractice disputes amounts to a sum lower than one percent of the $541 billion the nation spent on health care last year, doctors say fear of lawsuits plays a major role in health-care inflation.>>

(A) amounts to a sum lower>>

(B) amounts to less>>

(C) amounted to less>>

(D) amounted to lower>>

(E) amounted to a lower sum

The correct choice must feature a verb that agrees with the plural noun costs and refers to an action completed last year (past tense). The verb amounts in A and B fulfills neither condition, and amounts to a sum in A is redundant. The same redundancy occurs in E, and the construction a lower sum than is awkward and imprecise in the context of the sentence. In D, the adjective lower is erroneously used in place of the noun less as object of the preposition to. Choice C is best.　　我對og解釋沒問題～但我想問的是～這裡用less是為了當to的受詞（賓語）～那如果不是因為to的關係～單純要說低於1%能用lower than one percent嗎？？？大家來討論討論

低于1％、小于1％，可以用lower than one percent来表达。合理合法。

表述数字的时候用less和more

表示长短的时候用lower和longer

新东方是这么说的

請問您有例句嗎?? 我自己也覺得應該可以~但找不到例句

在这道题中，amount to more/less than是习惯用法。
而平时在正式场合，表达百分比的高低可以除了可以用more/less than之外，还可以用higher/lower than来表达，这本来就很合情合理。

来造个句子：the error rate in our test is lower than 10%.

关键是看词性！OG上说less 在这里是名词充当宾语。但是longman只有less做限定词和代词的说法。不过既然代词可以做宾语，所以和OG也没有太大的矛盾了。less 做determiner （限定词，就向the和some在 the car, some cars中的用法一样）或者pronoun的第一个意思：a smaller amount or not as much （表示一个小量），有less ... than 的结构。下面是longman给的用例：

less (...) than：                She knows less than I do about it.
less than 10/100 etc：           a distance of less than 100 metres  （顺便说一句，这个例子说明关键看词性，而且推翻了新东方）

many thanks !