The correct answer is A. reward.
The word “recompense” means to give someone something in return for their services or efforts. In this case, the speaker is saying that they don’t know how to repay the listener for the trouble they have taken. This suggests that the listener has done something helpful or kind for the speaker, and the speaker wants to show their appreciation.
Option B, “help,” is incorrect because it does not accurately reflect the meaning of the sentence. The speaker is not asking for help, but rather expressing their gratitude for the listener’s help.
Option C, “praise,” is incorrect because it does not accurately reflect the tone of the sentence. The speaker is not praising the listener, but rather thanking them.
Option D, “thank,” is the correct answer because it accurately reflects the meaning and tone of
the sentence. The speaker is thanking the listener for their trouble.