to the lowest level in two years vs to a two-year low level

[KItuz]

According to some economists, the July decrease in unemployment [u]so that it was the lowest in two years[/u] suggests that the gradual improvement in the job market is continuing.
[a] to what would be the lowest in two years
[b] to a two-year low level
[c] to the lowest level in two years.

Correct answer is c. On what basis do you eliminate a and b?

[prodizy]

A -> Would is used in two cases - When referring to future in the past and in hypothetical situations. In this question "would" is not doing that. also the sentence is lengthy

B -> I am not really sure about the grammatical nuances, but "to a two-year low", would have been correct.

[mankey]

Can someone throw some light on this one?

Thanks.