When $\alpha$-particles are directed at a thin metal foil, most of the particles travel straight through, but a few are scattered through a large angle. Which alteration would increase the fraction of $\alpha$-particles scattered through a large angle?
- Ausing $\alpha$-particles with greater kinetic energy
- Busing a double thickness foil
- Cusing a foil made of a metal with fewer protons in its nuclei
- Dusing a source emitting more $\alpha$-particles per unit time