Correct Answer - C
For isothermal process `V_(f)=2V_(0) :. P_(f)=P_(0)//2`
For isobaric process `V_(f)=V_(0)//2,T_(f)=V_(0)/2xx2V_(0) T_(0)=T_(0)/4`
For `P propto V` process
P-V must be straight line
`T propto V^(2)` Rightarrow V-T must be parabolic
`P^(2) propto T` Rightarrow P-T must be parabolic