Final answer:
The correct answer to the question is B. Surrender, as it is synonymous with 'relinquish' which means to give up control or cede power.
Step-by-step explanation:
The verb relinquish in the sentence 'I would not have relinquished sovereignty to the Coalition' means to give up or surrender control. In the options provided, A. Keep and C. Preserve are antonyms of relinquish, as they imply maintaining control or holding on to something.
Option D. Retain also means to continue to have something; therefore, it is not the correct choice. The correct answer is B. Surrender, which is synonymous with relinquish -- both mean to give up control or cede power.