Rubidium has two isotopes, $^{85}_{37}\text{Rb}$ and $^{87}_{37}\text{Rb}$. Which statement accounts for why both isotopes show the same chemical properties?
- AThey have the same number of protons.
- BThey have the same number of outer shell electrons.
- CThey have different numbers of neutrons.
- DThey have different mass numbers.