For irreversible expansion of an ideal gas under isothermal condition, the correct option is:

Since the process is isothermal, that means temperature will remain constant and internal energy depends only on temperature, so internal energy will also be constant that is $\mathrm{\Delta U}=0$

And since there is irreversible expansion, the entropy of the universe will change. ${\mathrm{\Delta S}}_{\text{total }}\ne 0$