Step 1: Review Radiation Types. - Alpha particles (\(\alpha\)): Consist of helium nuclei (\(^4_2He^{2+}\)) and carry a charge. - Beta particles (\(\beta\)): These are either electrons (\(\beta^-\)) or positrons (\(\beta^+\)), and are also charged. - Gamma rays (\(\gamma\)): High-energy photons, representing electromagnetic waves. Step 2: Determine the Answer. Gamma rays are uniquely electromagnetic waves. Alpha and beta particles are not electromagnetic waves, but are instead particles. Final Answer: \[ \boxed{\text{Gamma rays}} \]