GMAT Sentence Correction (SC) | Re: Proponents of relaxations that Censorship Board allow

My first instinct was to reject decisively all the choices except C due to that. However, even C is ungrammatical. What would you do then? At least this topic drove me to spot the MGMAT version, which I liked much for the concept of double referencing of a pronoun in a given sentence. IMO, You are justified in rejecting the four choices, A,B,D and E on
S-V number error