Answer:
C). To emphasize that the Japanese attack was deliberate and treacherous.
Step-by-step explanation:
Repetition is demonstrated as one of the varied devices that are employed by the authors to convey the intended meaning as it creates a specific effect or emphasizes a particular point to serve the desired purpose of the author(to instill a particular idea or message).
In the given excerpt from President Roosevelt's speech, the purpose of repetition of the idea 'implications(loss of life and safety) led by the Japanese attacks' in order to 'emphasize that these attacks were deliberate and treacherous'. He intends to reflect the damaging impacts (through repetition) of such attacks and imply that these were duplicitous and fraudulent attempts. Thus, option C is the correct answer.