Final answer:
The sentence discusses how watchmen prevented an attack by firing warning shots into the air. 'Thwarted' means 'prevented', making it the correct option from the given list: prepared, prevented, caused, wanted.
Step-by-step explanation:
The phrase 'the watchmen thwarted an attack by firing warning shots into the air' is written in the English language, and it involves the use of vocabulary and comprehension. The word 'thwarted' in the sentence means 'prevented'. Therefore, in this context, the correct option among the provided (prepared, prevented, caused, wanted) is 'prevented'.The watchmen who were presumably guarding the camp 'thwarted' or prevented an attack from the enemies by firing warning shots into the air, hence averting a possible clash or invasion.
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