If the daughter of Theresa is the mother of my daughter in a family relation puzzle what is my relationship to Theresa?

Introduction / Context:
This family relation puzzle checks your ability to follow generational links and in-law relationships carefully. Such questions are common in reasoning sections of competitive exams. The challenge is to convert a sentence that uses terms like daughter and mother into a simple family tree and then read off the correct relationship between the speaker and another named person, here Theresa.

Given Data / Assumptions:
- Statement in the puzzle is that Theresa daughter is my daughter mother.- My daughter mother is the woman who is married to me if I am male.- The puzzle wording and the answer options suggest that the speaker is male because only then the term son-in-law is meaningful.- Standard meanings of relations like daughter, mother, and in-law are used.

Concept / Approach:
The solving idea is to rewrite the relation in several small steps. First you understand who is my daughter mother. Then you observe that this woman is described as the daughter of Theresa. Finally you identify how a man is related to the mother of his daughter and then how that link connects him to Theresa. Turning words into a mental diagram or quick sketch is often the easiest approach.

Step-by-Step Solution:
Step 1: Consider the phrase my daughter mother. If the speaker is male then the mother of his daughter is his wife.Step 2: The puzzle says that this same woman is the daughter of Theresa. So the wife of the speaker is the daughter of Theresa.Step 3: If a man is married to the daughter of a woman then that woman is his mother-in-law and he is her son-in-law.Step 4: Therefore Theresa is the mother-in-law of the speaker and the speaker is the son-in-law of Theresa.Step 5: Among the options given, the role of the speaker relative to Theresa is captured exactly by the term son-in-law.

Verification / Alternative check:
To verify this reasoning you can assign simple names. Let the speaker be Raj. Let Raj wife be Anu. Let Theresa be the mother of Anu. Anu is the mother of Raj daughter. In that case Raj is married to the daughter of Theresa, which makes Raj the son-in-law of Theresa. This concrete example confirms that the abstract reasoning is correct.

Why Other Options Are Wrong:
Option B daughter-in-law would describe the relation of a woman married to a person son, not of a man married to a person daughter, so it does not fit the puzzle.Option C grand mother is incorrect because the speaker is clearly not in an older generation than Theresa. Theresa is the parent of the speaker wife.Option D grand daughter is also incorrect because the speaker is not the descendant of Theresa in that way. The riddle talks about a marriage link, not an extra generation downward.

Common Pitfalls:
A frequent mistake is to read Theresa daughter is my daughter and then to think that the speaker is directly the child of Theresa. Another common error is to ignore gender markers and assume the speaker might be female. However the presence of son-in-law and daughter-in-law in the options strongly hints that the speaker is male.

Final Answer:
In this puzzle the speaker is the son-in-law of Theresa.