Answer:
B. To support a claim about how quickly New York's population increased.
Step-by-step explanation:
In the given passage about the surge of immigrants in America, the author includes how most of the immigrants came through the Ellis Island Immigration Station. This New York harbor would be the main point of entry for most of the "newcomers".
By including this information about the station, the author is providing support to the claim that New York City is "overwhelmed" by the surge in the immigrants who settled on the place they landed- New York. So, the city became more crowded, although it was already crowded, with "various types of streetcars vying for space on the roads." This added to the increased population of the city.
Thus, the correct answer is option B.