GMAT Sentence Correction (SC) | The managers were asked to rate their depth

The managers were asked to rate their depth of knowledge having been increased as a result of the emergency simulation, and in each area, they reported large gains.

(A) their depth of knowledge having been increased
(B) how much their depth of knowledge had increased
(C) if they had more knowledge
(D) how deep their knowledge is
(E) their knowledge depth

---