What does nomadic hunter-gatherers and cave dwellers mean?

The collapse of the roman empire most likely to empower the catholic church because

What led to the environmental damage that caused the dust bowl? 1. desert winds emerging from the southwest 2. rotating crops every year and having fallow land 3.overplanting throughout the great plains 4.a year-long drought

Which of these were achievements of the safavid dynasty? check all that apply.