ambiguous or not?

[tankobe]

Although i had registered for GMAT, until almost Augest, i did not begin intensively to study it.
(A) until almost Augest, i did not begin intensively to study
(B) until almost Augest i had not begun intensively studying
(C) not until almost Augest were i to begin intensively to study
(D) it was not almost until Augest when i began to intensively study
(E) it was not until almost Augest that i intensively began studying
KEY is E
(1) The red parts are diffcult.could any one tell what the intensively in each option is supposed to modify, in other words, is there ambiguity in A,B,C, and D?
(2)is when in D ok? (can it refer to when clause? or, provided this context, it do not need to refer anything)
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here is another example[in which increasely seems in wrong place]:nuclear attack submarines prowl their familiar haunts deep within the oceans of the world these days, they increasingly are engaged in missions far different from the tasks for which they were built and for which their crews were trained over the last forty years