Hello. 1a. Voters can deny the impact of attractiveness on electability all they want, but evidence has continued to confirm its troubling presence.(Korea university entrance exam) The relative pronoun 'that' is omitted between 'electability' and 'all'. 'all' is the adverb here and means 'much' or 'really'. The antecedent of the omitted relative pronoun(that) is 'electability'. Then, does this way make sense? Thank you always~.