The answer I think is Captive Africans.
A common feeling of those in Angel Island was that the US police and military on Angel Island was evil and that they were oppressing those who wanted to enter the country. He would probably describe how they would often get beaten up or how disease would easily spread since they were on an island or how there wasn't enough food.
As proved by the transatlantic flights of Lindbergh and Earhart, postwar airplanes were engineered to fly greater Distances so the answer is. A.
Washington Gladden's ideas would most closely be tied to Reconstruction period in United States history. The correct option among all the options that are given in the question is the fourth option or option "D". Washington Gladden was a minster and a pastor and he was helping in the reconstruction of religion.