How did rutherford change the model of the atom?

a.
he used an experiment with gold foil to prove that an atom had a positive nucleus in the middle and was surrounded by negative electrons.

b.
he used thought problems to determine that matter could be divided into smaller pieces until it got to the atomic level.

c.
he used an experiment with cathode ray tubes to prove electrons existed when they changed the color of a gas.

d.
he used various experiments to prove that atoms of the same element have the same mass.