Option (a) is wrong ; since in adiabatic process V $\ne$ constant.

Option (b) is wrong, since in isothermal process T = constant

Option (c) & (d) matches isotherms & adiabatic formula :

${\mathrm{TV}}^{\mathrm{\gamma }-1}=\mathrm{constant}\&\frac{{\mathrm{T}}^{\mathrm{\gamma }}}{{\mathrm{p}}^{\mathrm{\gamma }-1}}=\mathrm{constant}$