Adverse remarks against the leader provoked his followers.

The correct answer is: D. unfavourable

Adverse remarks against the leader provoked his followers. This means that the remarks were negative and caused the followers to become angry or upset. This is an example of unfavourable

The other options are not correct because they do not accurately describe the situation.

• Dangerous is not the correct answer because the remarks did not cause any physical harm.
• Unnecessary is not the correct answer because the remarks were not necessary to provoke the followers.
• Severe is not the correct answer because the remarks were not particularly harsh or severe.

Therefore, the correct answer is D. unfavourable.