Concept:The idiom "at arm's length" means keeping someone at a deliberate distance, avoiding closeness or intimacy.
Explanation:When you keep a person at arm's length, you do not allow them to come near you emotionally or socially.
It suggests a cautious attitude of staying aloof and not forming a close relationship.
In the given sentence, Ammon has always kept his enemies at arm's length.
This means he deliberately avoids any close contact or familiarity with them.
Such behaviour is best described as shunning them.
It does not mean abusing, threatening, or trusting them, because all these actions involve some level of interaction or reliance.
Therefore, the idea of staying away from his enemies matches option B.
Answer:B. shunned them