Consider two cases :

1) P = -25, 0, 25 Q= -25,-25, 0
2) P = -25, 0, 25 Q= -50,-25, 0

As in above two cases given condition is well full filled , like both have common -25, 0 and range is 50 in all cases

If we take 1st case then then R = -25, 0, 25 & S = -25, -25, 0, 0, 25 , 25 both R and S have range 50 (X=Y=50)

If we take 2nd case then then R = -25, 0 & S = -50, -25, -25, 0, 0, 25 thus Range of R is 25 and Range of S =75 (X=25 and Y=75)

X : least value = 25 and Highest Value =50
Y : least value = 25 and Highest Value =75

Quantity A : 25 + 75 = 100
Quantity B : 50 + 50 = 100

thus C