Concept:The phrase "throw in the towel" is an idiom that means to admit defeat or stop trying after repeated failures.
Explanation:In the sentence, he made several attempts to claim the child.
Since he finally "threw in the towel," he stopped trying because he could not succeed.
The idiom refers to giving up or accepting that one has lost.
It does not mean he finally succeeded, became confident, or stopped caring.
Therefore, the most appropriate interpretation is that he accepted defeat.
Answer:B. accepted defeat