To establish the relationship between the man and Rani, the statement requires a systematic analysis:
- Rani's statement: "He is the son of my mother's only daughter."
- Analysis of the phrase:
- My mother's only daughter: This phrase unequivocally identifies Rani, as she is her mother's sole daughter.
- The son of (Rani): Consequently, the man is Rani's son.
- Therefore, the man is Rani's Son.
- Alternatively, if the statement implies "Rani is not referring to herself as her mother's only daughter:"
- My mother's only daughter: Rani is still implicitly indicated.
- In this interpretation, the son of Rani (who is her mother's only daughter) would be Rani's Brother.
Based on the provided context and the most logical interpretation, the man is Rani's Brother.