Given the table below, what is the chemical formula for a compound between Rb and the nitrate ion NO3-1?

nitrate ion NO3-1

phosphate PO4-3

sulfate SO4-2

acetate C2H3O2-1

ammonium NH4+1

chromate CrO4-2

carbonate CO3-2

dichromate Cr2O7-2

permanganate MnO4-1

sulfite SO3-2

RbNO 3
Rb(NO 3) 2
Rb 2NO 3
Rb 2(NO 3) 3