I believe it is D. International date line, because the question holds the answer. When you say "Different days" it kind of gives the answer away.
Hope this helps :)
3.) People that share a common language, culture, or history are referred to as an ethnic group. The answer is B.
4.) There have been many issues in Canada where Quebec wants to become an independent country because of it being more French. The answer is C.
5.) The Canadian Sheild is not arable land. The land is very hard and has thin soil. The answer is A.
