Find the antonym of PROCLAIM 

Concept: To proclaim means to make a public announcement.

As the antonym of proclaiming must be a term that signifies concealing or not releasing information, conceal is the correct answer because 'conceal' means to conceal or prevent information from being known.

Option A is erroneous since 'denounce' means to publicly criticize another person, which is not the antonym of proclaiming.

Option B is inaccurate because 'pretend' implies acting in a certain way in order to persuade others that something is not true, and it is not the antonym of proclaiming.

Option C is inaccurate since 'willing' implies that they are not prepared or ready to perform a duty, and thus it is not the antonym of proclaiming.

Hence, option D is the correct answer.