Hello set2018
Question is , there is some operator $\square$ , for which truth table is given , like when first operand is T and second operand is T , o/p will be T. When first operand is T and second is F , o/p will be T...as so on..now just on the bases of this truth table , you have to find truth tabes for Q'$\square$P' , P$\square$Q' , P'$\square$Q , P'$\square$Q' ,now compare those truth tables with truth table for P∨Q , see which one exactly matches with that one.