‘Adverse’ means not favourable or harmful. So, the best fit as meaning of the answer is Option D ‘Unfavourable’ which also means critical or negative. The context of the sentence is that unfavourable remarks against the leader provoked his followers. Option A ‘Dangerous’ means unsafe or risky . Option B ‘Unnecessary’ means not needed . Option C ‘Severe’ means serious. Thus, the correct answer is option D, ‘Unfavourable’.