Answer: Option (D) is the correct answer.
Explanation:
Parent atom is the atom which undergoes radioactive decay in a nuclear reaction. After the decay, this parent atom results in the formation of different products.
The given radioactive decay reaction will be as follows.
[tex]^{129}_{53}I \rightarrow ^{129}_{54}Xe + ^{0}_{-1}e[/tex]
Here, beta particle is emitted along with the formation of [tex]^{129}_{54}X[/tex].
Thus, we can conclude that in this reaction the parent atom is [tex]^{129}_{53}I[/tex].
