Im pretty sure its Russia
I am not 100% sure but I believe the answer is C.
The two main types of sources are present sources (people their at the time) and post sources (overviews of what happened at the time) I am pretty sure this is correct
1) maintaining current relationships - with your friends and family
2) establishing new relationships - and risking being lonely for the first weeks
3) not having a social support in the place (someone to cook for you when you're sick
4) additional costs of renting a house in a new place and making sure you have all the utilities.