When $\alpha$-particles are directed at a thin metal foil, most of the particles travel straight through, although a small number are scattered through a large angle. Which change would raise the proportion of $\alpha$-particles scattered through a large angle?
- Ausing $\alpha$-particles with greater kinetic energy
- Busing a foil made of a metal with fewer protons in its nuclei
- Cusing a double thickness foil
- Dusing an alpha source with a higher activity