What contribution did niels bohr make to atomic theory?
a. he performed an experiment that determined the charge of the
electron
b. he made a model of the atom called the plum-pudding model.
c. he discovered that the photoelectric effect was caused by light
shining on metal
d. he made a model of the atom, with electrons circling the nucleus.

The contribution that Niels Bohr make to atomic theory is He made a model of the atom called the plum-pudding model.

Atomic theory  can be regarded as scientific theory which explains that matter is composed of particles called atoms.

Therefore, Niels Bohr made a model of the atom called the plum-pudding model.

Learn more about atomic theory at;

link

the answer for sodium is 0.186

the answer for rubidium is 0.251