Here's why:

* Hg₂ represents the mercury(I) ion, which is a diatomic ion (two mercury atoms bonded together).

* (NO₃)₂ represents two nitrate ions (NO₃⁻).

* The Roman numeral I in parentheses indicates the oxidation state of mercury, which is +1 in this compound.

Therefore, the correct name is Mercury(I) Nitrate.