E is the sister-in-law of B. A and C are sisters. D is the daughter of B. H is the nephew of C. A is the paternal grandmother of D. F is the brother-in-law of C. G is the son of H. B has no siblings. There are two married couples in the family. C is not married.

How is G related to C?

To determine how G is related to C, let us analyze the relationships step-by-step:

1. A and C are sisters: A and C are females who are siblings.
2. A is the paternal grandmother of D: Since A is the grandmother of D on the father's side, D must be the child of A's son. Let's find A's son.
3. D is the daughter of B: This means B is a parent of D. Since A is the paternal grandmother of D, B must be the father of D (A's son). Therefore, B is male, A is B's mother, and D is female.
4. B has no siblings: B is an only child.
5. E is the sister-in-law of B: Since B has no siblings of his own, his sister-in-law must be his wife's sister. Let us find B's wife.
6. There are two married couples in the family: One married couple is B and his wife. C is not married, so C cannot be part of the married couples. Since A is a grandmother, A must have been married (likely to B's father, who is not mentioned or is deceased).
7. F is the brother-in-law of C: Since C is unmarried and A is her sister, F must be married to C's sister A. Thus, A and F are the second married couple. Since F is the husband of A, F is the father of B (A's son). This matches F being the brother-in-law of C (sister's husband).
8. E is the sister-in-law of B: B is married. B's wife must have a sister E. So, B is married to someone, and that person's sister is E.
9. H is the nephew of C: C's sister is A. The son of A (which is B) is C's nephew. Since H is also a nephew of C, H must be a male cousin or another sibling. But wait, B has no siblings. A has only one son B. H is a nephew of C. H could be B's son, but B's children would be grand-nephews of C. Wait, if C is the sister of A, then C's nephew is A's son, which is B. However, H is also a nephew of C. Could H be the son of another sibling? C and A are sisters. If there are no other siblings, B is the nephew of C. What if H is the husband of someone, or is B itself? No, "H is the nephew of C". Let's re-evaluate. If B has no siblings, and H is the nephew of C, and C has only one sister A (who has son B), then H must be B. Thus, H and B are the same person (nephew of C).
Let's check if H = B: H is the nephew of C, B is the son of A (C's sister), which makes B the nephew of C. Yes, H and B are the same person! (Nephew of C).
10. G is the son of H: Since H is B, G is the son of B. Therefore, G is the brother of D.
11. How is G related to C?
Since G is the son of H (B), and H (B) is the nephew of C (the son of C's sister A), G is the grand-nephew or grandson in the extended generation. Let's look at the options: ["Son", "Grandson", "Granddaughter", "Father"].
Since G belongs to the generation of C's sister's grandchildren (A is G's grandmother, so C, being A's sister, is in the grandmother's generation relative to G), G is the grandson (or grand-nephew, often simplified to grandson in such options) of the grandmother's sibling C.

Therefore, G is the Grandson of C.