When Ankith saw Sanvi, he recalled, "She is the daughter of the father of my daughter's mother." Who is Sanvi to Ankith?

Introduction / Context:
This blood relation problem uses a slightly complex phrase involving my daughter's mother. Such phrases commonly describe the speaker's spouse and in laws. The goal is to reduce the wording to a simple description like wife's sister or sister, and from that choose the correct relation term. This question focuses on the sister in law relation.

Given Data / Assumptions:

• Ankith is the speaker.
• My daughter's mother is Ankith's wife.
• The father of my daughter's mother is Ankith's father in law.
• Sanvi is described as the daughter of that father in law.
• We assume that this daughter is not the same person as Ankith's wife, representing a different daughter of the same father.

Concept / Approach:
The expression my daughter's mother refers directly to Ankith's wife. The father of my daughter's mother is therefore Ankith's father in law. If Sanvi is a daughter of this man, she is a daughter of Ankith's father in law. This means that Sanvi is a sister of Ankith's wife. A sister of one's wife is one's sister in law. Hence, Sanvi is the sister in law of Ankith. The question asks for Sanvi's relation to Ankith, so sister in law is the appropriate choice.

Step-by-Step Solution:
Step 1: Interpret my daughter's mother as Ankith's wife, since she is the mother of his daughter.Step 2: The father of my daughter's mother is Ankith's father in law.Step 3: Sanvi is introduced as the daughter of this father in law.Step 4: Thus, Sanvi is a daughter of Ankith's father in law and a sister of Ankith's wife.Step 5: A sister of one's wife is called a sister in law.

Verification / Alternative check:
Build a sample family: father in law has two daughters, one married to Ankith and the other being Sanvi. The first daughter has a daughter with Ankith. When he says the father of my daughter's mother, he refers to his father in law, whose other daughter is Sanvi. At every step, the relationships match the description. There is no way for Sanvi in this structure to become his sister or daughter in law given the starting point, so sister in law is the unique fit.

Why Other Options Are Wrong:
Sister would require Sanvi to share parents with Ankith, which is not suggested.Daughter in law would require Sanvi to be married to Ankith's son, which is never indicated.Cousin assumes shared grandparents through siblings of parents, which is not described.Aunt would require Sanvi to be a sister of one of Ankith's parents, which contradicts the information.

Common Pitfalls:
Sometimes students automatically take daughter of my father in law to mean my wife, ignoring the possibility of multiple children. This would collapse Sanvi and the wife into one person and cause confusion. Always check if the wording uses only daughter or specifies a unique child. When it does not, it usually signals another sibling such as a sister in law in these puzzles.

Final Answer:
Sanvi is related to Ankith as his Sister-in-law.