Answer:
The people of Japan are good-looking and well-mannered.
Step-by-step explanation:
In order to detect a form of subjectivity, it is important to look for any form of personal opinion or impression. A comparison is a good way of distinguishing subjectivity from objectivity.
The people of Japan live 1,500 miles from the mainland.
If we pay close attention to the information given in this sentence, we can see that it is factual information and that it can be easily verified. The narrator abstains from commenting on this fact. He only delivers an objective truth.
The people of Japan live on an island.
Here again we have pure encyclopedic data. The author's attitude towards the Japanese and their island life stays unknown and in the shadow of reporting information.
The people of Japan are good-looking and well-mannered.
There is no survey to conduct in order to receive a clear and unanimous judgement on the looks and manners of a nation. Firstly, it is impossible to settle with a general but also factual and objective opinion and secondly, this very judgement requires subjectivity. It requires the involvement of our emotions because it is the impression we are left with that counts, and not precise information. The author also had to have experienced some contact with the people of Japan so as to be able to report on their good manners.
The people of Japan exercise no authority over other nations.
This is a questionable sentence. One can argue that it is the author's personal experience that lead him to a conclusion on the Japanese's attitude toward other nations. But a closer look at the form and the tone of this sentence may help us decide: the tone is that of an objective observer and the negative form convinces of his undivided opinion and imposes the impression of objectivity.
The clearest and therefore the best example of subjectivity of the author can be found only in the third sentence, where he provided us with a glimpse of his own personal experience with the people of Japan which lead him to a subjective judgement.