Final answer:
The term used to describe a prolonged series of retaliatory acts is a vendetta, often fueled by revenge.
Thus, the correct option is 1).
Step-by-step explanation:
The term used to describe a prolonged series of retaliatory acts is vendetta. A vendetta is a prolonged and bitter feud or rivalry, typically between two families or clans. It involves a cycle of revenge, where each party seeks to avenge previous actions.
For example, in the Northeast region of the United States, warfare was motivated by revenge, leading to a cycle of war known as the 'Mourning Wars.' Each group sought to avenge those killed in earlier wars or skirmishes, perpetuating the cycle of violence.
In summary, a vendetta is the term used to describe a prolonged series of retaliatory acts, often fueled by revenge.
Therefore, the correct option is 1) A vendetta.