Plleeeaaassee !

how many protons, neutrons, and electrons does rubidium-87 contain? *

a) 87 protons, 85.5 neutrons, 87 electrons
b) 37 protons, 37 neutrons, 37 electrons
c) 37 protons, 87 neutrons, 37 electrons
d) 37 protons, 40 neutrons, 37 electrons