Which error in the sentence should be corrected when editing?

The first Penal Transportation Act in 1718 allowed English courts to sentence convicts to seven years' transporation to America.

A. awkward phrasing

B. wordiness

C. punctuation

D. spelling error

The correct answer is A. It is difficult to understand the part of "seven years' transportation to America". It seems to me that you should use a passive structure so as to place the kind of sentences that English courts were allowed to give first, and after mention that the first Penal Transportation Act was the one which introduced this change. The other answers do not apply to this sentence, there are no puntuation and spelling mistakes, and there are no unnecessary words.