Answer:
The best statement which describe Javier's research question is:
O. It is specific but not too narrow, and is phrased to allow for an in-depth response.
Step-by-step explanation:
From the question which was asked by Javier, we could see that, he asked a specific question in his question to obtain the positive or negative effect og life in Japan as a result of Treaty of San Francisco.
On the other-hand, it is not too narrow due to the fact that, the effect could range from education, to history or from military hardware to medical researches. It is phrased to allow for in-depth response which would take up all the time in the history class while not providing opportunities for all students to contribute within the allocated time frame.