B is the daughter of A. C is the husband of B. D is the son of C. How is A related to D?

The correct option is Cannot be determined.

Let us analyze the relationships step-by-step to determine how A is related to D:
1. "B is the daughter of A" implies that A is the parent of B (either the father or the mother). B's gender is female.
2. "C is the husband of B" means C is male and B is his wife.
3. "D is the son of C" means D is the child of C and B. Since D is C's son, D is male, and B is D's mother.
4. Now, A is the parent of B (D's mother). Therefore, A is the grandparent of D.

However, the question does not specify the gender of A. A could be either the maternal grandfather or the maternal grandmother of D.
Since the gender of A is unknown, the exact relationship of A to D cannot be determined from the given information.