Which of these new deal opponents advocated an idea that was adopted during the second new deal ? ?
a) francis townsend
b) herbert hoover
c) huey long
or
d) father coughlin

From those aforementioned, the one who advocated an idea that was adopted during the Second New Deal was Francis Townsend, whose agitation for the "Townsend Plan" for old-age pensions had some influence on FDR introducing Social Security old-age pensions in 1935. The answer to your question is A. I hope that this is the answer that you were looking for and it has helped you.