Amounts or Amounted...

[sourav106]

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 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

[rockerz]

the word 'sum' is redundant in (A) and (E)..
use of lower is wrong..amounts should be discussed in less/more and not low/high..

left with (B) and (C)..we do seem to need the past tense here to || with 'spent'..and certainly direct costs "amounts" seem to be wrong..the verb should be amount for (B) to be worth considering..

Hence by POE, I get (C)..which doesnt violate any basic grammar rules at least.