💡 Detailed Explanation
The grammar pattern '～からには' expresses a strong reason, meaning 'now that... / since...'. It's followed by a sentence expressing obligation or determination. The pattern '～ずにはすまない' means 'must do...' or 'cannot avoid doing...' due to social or moral reasons. Combining them creates the meaning 'Now that I have spoken so rudely, I will have to apologize.' The correct word order is 「聞いた」「からには」「謝ら」「ずには」. Therefore, the word that goes in the star position is 「謝ら」.