What is the most painful and/or annoying problem that foreign exchange students face when they study in America?

The correct answer is - the language barrier leads to social and cultural distance.

Explanation:

There are various problems that foreign students experience during the study in America which does not allow them to easily adjust to the newer place. These problems and issues include cultural or social shock, homesickness, communication due to the language barrier, and many more.

Among all the language barrier and cultural or social distance are the most annoying issue for the foreign students during the study period as they even they are able to excel at expressing feelings however, they still not able to understand nuances and would not able to get colloquialisms and local accents.