Select the option that can be used as a one-word substitute for the given group of words.

One who is hostile and violent

Aggressive

The word "Aggressive" accurately represents a person who is hostile and prone to violent behavior. It describes someone who displays a readiness to attack, confront, or harm others physically or verbally. In the given group of words, "one who is hostile and violent," the word "aggressive" best captures the behavior and attitude being described.

"Idle" means being inactive, lazy, or lacking purpose. It does not convey the sense of hostility and violence.

"Legendary" refers to something or someone who is famous or renowned for their exceptional achievements or qualities. It does not relate to being hostile and violent.

"Agreeable" describes someone who is pleasant, willing to agree, or easy to get along with. It is the opposite of hostile and does not convey the violent aspect.

Therefore, "Aggressive" is the most appropriate one-word substitute for the given group of words as it directly represents someone who is hostile and prone to violence.