Answer
Alpha and beta particles are pushed in opposite directions by an electric field. Gamma rays are unaffected.
Work Step by Step
Alpha and beta radiation consist of helium nuclei and electrons, respectively, so alphas are positively charged, and betas are negatively charged. Positive and negative charges feel forces in opposite directions when they encounter an electric field.
Gamma rays are electromagnetic waves, have no electric charge, and are unaffected by an electric field.