From GMAT prep software:
G.W.C. dedicated his life to the economic strengthening of the south with improvement of soil and diversification of crops (...).
My choice: the strengthening of the economy of the south through improving soil and crop diversifying.
Correct answer choice: strengthening the economy of the south through soil improvement and crop diversification.
Regardless "through improving soil and crop diversifying", which I understand why is wrong. I'm clueless on why "strengthening the economy" is preferred over "the strengthening of the economy".
Also, on the grammar point of view since I'm not a native speaker, can someone, please, explain me better the construction VERB TO ING-VERB? Generally speaking, don't you need an INFINITIVE FORM after the preposition TO?
(G.W.C. dedicated his life to strengthening the economy of the south through soil improvement and crop diversification).
Thanks!