1 mole of each of X1 ,X2,X3. with vanderwaal's constants  (in atm L3 mol-2) 1.0,3.8, 2.1 respectively is kept separately in three different vessels of equal volume at identical temperature. Their pressures are observed to P1, P2, and P3 respectively. on the basis of this data alone, select the correct option (neglect the effect of 'b'):