A certain gas is taken to the five states represented by dots in the graph. The plotted lines are isotherms. Order of the most probable speed v_p of the molecules at these five states is:

Stages 1 and 2 are at same temperature also stages 4 and 5 are at same temperature.
As,  $V_P$  is more at higher temperature and same at all stages at equal temperature.
$\therefore V_{P3}>V_{P1}=V_{P2}>V_{P4}=V_{P5}$
(As  ${\text{T}}_3>{\text{T}}_2={\text{T}}_1>{\text{T}}_4={\text{T}}_5$ )
Hence (A).