An increased level of entrepreneurship in the metropolitan area was brought about not by immigrants who arrived in a substantial influx, which was the case in cities several decades ago, but adjustments to the federal tax code that heavily favor the self-employed.
(A) brought about
not by immigrants who arrived in a substantial influx, which was the case in cities several decades ago,
but Incorrectparallelism error - ..........not by..................., but...........
(B) brought about
not by a substantial influx of immigrants, the case in cities several decades ago,
but Incorrectparallelism error - ..........not by............., but ..............
(C)
brought about not by a substantial influx of immigrants, as was the case in cities several decades ago, but by Correct(D)
not brought about by a substantial influx of immigrants, which was the case in cities several decades ago,
but was brought about by Incorrectparallelism error - .............not brought about by................., but was brought about by...............
(E)
not brought about by immigrants who arrived in a substantial influx, the case in cities several decades ago,
but by Incorrectparallelism error - .................not brought about by............, but by ................