Option 1 -> pragmatic means practical and realistic, but doesn't directly oppose being easily trusting.
Option 2 -> cynical means distrustful of others' motives, which is opposite in spirit but not the most precise antonym.
Option 3 -> Skeptical means questioning and not easily convinced, the direct opposite of readily believing.
Option 4 -> qullible is not a standard or recognized English word.
Hence, Option 3: Skeptical -> "Credulous" means readily believing or trusting without questioning, while "skeptical" means having doubts and not easily convinced. A skeptical voter would question the politicians' exaggerated promises rather than readily believing them. -> correct