•unemployment—industrialization
•soil depletion—abundant resources
•political persecution—personal liberties

the items above are examples of

unsustainable development

overpopulation

push-pull factors

urban form

The items above are examples of : 
Push - Pull Factors.
Push factors are the factors that drove away people to get outside a specific areas (usually negative)
Pull factors refer to the characteristic of an area that attract the migration.

The sun's parallax would be 180 degrees, greater than which you can't get.  so a. would be your anwser