I only see 3 excerpts.....those I can see would be as follows:
1) Society and class
2) humankind and nature
3) evolution
Don't know why the other 2 excerpts don't show up (for me)
The best option is D studied.
This word denotes a measured, even-handed approach to the issue. So, it should be :Current immigration policy must be studied before new proposals can be made.
Because they wanted to return to there home land