For isotherm, $\Delta T=0 \Rightarrow \Delta U=0$
For adiabat, $\Delta Q=0 \Rightarrow \Delta U=-\Delta W<0$
For isobar, $\Delta V \propto \Delta T \Rightarrow \Delta T>0 \Rightarrow \Delta U>0$
Let the internal energy change be $\Delta U_{1}, \Delta U_{2}, \Delta U_{3}$ for the isotherm, adiabat, isobar respectively.
Then $\Delta U_{3}>\Delta U_{1}>\Delta U_{2}$
Thus option $b$ is only false


