After gradual declension down to about 39 hours in 1970, the workweek in the United States has steadily increased to the point that the average worker now puts in an estimated 164 extra hours of paid labor every year.
A) After gradual declension down.
B) Following a gradual declension down.
C) After gradual declining down.
D) After graduay declining.
E) Following gradualy declining.
Between (D) & (E), OG says, the phrase must be started by the preposition(after) not the participle (following). But it doesn't explain why. Can someone/instructors explain why?
Thanks