Yes it can be

The solution I understood the tree made in the solution but there is another tree that can be made with the given info- F(female) is married to A(male) and they have 2 children D(son) who is the husband of C(female) and B(daughter). E is said to be the grandfather of D (can be either maternal/paternal). This tree does not violate any rules I guess and according to this tree the answer should be D is the son of F.

The solution I understood the tree made in the solution but there is another tree that can be made with the given info- F(female) is married to A(male) and they have 2 children D(son) who is the husband of C(female) and B(daughter). E is said to be the grandfather of D (can be either maternal/paternal). This tree does not violate any rules I guess and according to this tree the answer should be D is the son of F.