Final answer:
The correct formula for manganese (II) nitrate is Mn(NO₃)₂, which signifies that manganese is in a +2 oxidation state.
Step-by-step explanation:
The correct formula for manganese (II) nitrate would be Mn(NO₃)₂. Since manganese can have multiple oxidation states, the number in parentheses indicates the oxidation state of manganese in the compound. In this case, '(II)' signifies a +2 oxidation state for manganese, making option B) manganese(II) nitrate the correct answer. Note that this is distinct from manganese(IV) nitrate which would contain manganese in a +4 oxidation state, and manganese nitride which is a different compound.