Guven Z is Grand Father Of S This can be happened only if P is married to R or Q is married to R
A)X is mother in law of R ( as Gender is not given so X can be mother in law of R) --------- May be True
B)P and R are not married to each other (We can't say whether PR are married or QR are married since S is grand Daughter of Z)
so Option B May be True
C) P is Son of X and Y ( as P gender is not given, P can be son) ------ May be True
D) Q can't Married to R ( Q May Marry R if Q and R are Opposite genders ) ----- This is false
So Option D