Correct option is C
Explanation-
Statement A - The activation of Sox9 gene promotes testis determining pathway - Correct.
Sox9 is activated downstream of SRY in males. It is essential for testis formation by promoting Sertoli cell development and AMH (Anti-Müllerian Hormone) production.
Statement B - The accumulation of β-catenin is critical for activating ovarian development - Correct.
β-catenin is a key player in the ovarian development pathway, opposing Sox9. Its accumulation inhibits testis formation and supports ovarian fate.
Statement C - R-spondin 1 (Rspo1) stimulates the Disheveled protein, thus promoting testis determining pathway - Incorrect.
R-spondin 1 (Rspo1) is not involved in testis development. It works with Wnt4 to promote ovary development. It activates the Wnt/β-catenin pathway, which suppresses testis formation. So saying it promotes testis determination is wrong.
Statement D - Though Wnt4 is expressed in the bipotential gonads, it is an important factor in ovary determination - Correct.
Wnt4 is essential for ovary development. Knockout of Wnt4 leads to partial masculinization of XX gonads.
Final Answer: Option C is incorrect which makes it a correct answer.
