The Federal Reserve Board assumes primary
responsibility of the regulation for this nation's
commercial banks and savings institutions.
(A) Board assumes primary responsibility of
the regulation for
(B) Board's assumption of primary
responsibility for the regulation of
(C) Board's assuming primary responsibility to
regulate
(D) Board assumes primary responsibility for
the regulation of
(E) Board regulates primary responsibility for


Kaplan GMAT says the idioms are responsible for, responsibility to but here the choice C is taken as wrong. Please tell what is the correct idiom usage?

Best Regards,
JOHN