D is correct imo.
The local chapter of the Bike Riders' Association has repeatedly railed against the municipal authorities, protesting that requiring them to wear bike helmets, even on off-road cycling paths, limit their civil liberties.
(A) requiring them to wear bike helmets, even on off-road cycling paths, limit their civil liberties---> Wrong. Ambiguous
them which must refer to
cyclists/riders, but the here
them illogically refers to
municipal authorities. Requirements were not imposed by authority on itself. Moreover, the plural verb
limit does not agree with
requiring.
(B) to require that they wear bike helmets, even when cycling off-road, limits their civil liberties--->Wrong.
Them, again refers to
authorities.(C) the requirements of wearing bike helmets, even on off-road cycling paths, is a limitation on cyclists' civil liberties----> Wrong. Subject(requirements) and Verb(limits) do not agree.
(D) requiring cyclists to wear bike helmets, even when cycling off-road, limits their civil liberties----> Correct
(E) requiring helmets even though during off-road cycling, limits their civil liberties---->Wrong.
Their does not have an a proper antecedent. If their refers to
authorities, it woul create an absurd meaning.
Even though is not correct here.