Radiation Or(and) Particles Emerge(s) from a Radioactive Sample $\alpha$ Rays
B)The Beam Is Only

Radiation or(and) particles emerge(s) from a radioactive sample.These products from the sample are allowed to pass through a narrow slit and may be considered a beam.The beam is passed between two plates that carry opposite electrical charge.The experimental region contains no magnetic fields.It is observed that the beam is deflected toward the negatively charged plate. Which one of the following statements is the best conclusion for this situation?

A) The beam is only $\alpha$ rays.
B) The beam is only $\beta$ ^- rays.
C) The beam is only $\gamma$ rays.
D) The beam could be either $\alpha$ rays or $\beta$ ⁺ rays.
E) The beam could be $\alpha$ rays, $\beta$ ⁺ rays, or $\gamma$ rays.