Districts with limited economic opportunities and frequent droughts tend to be major sources of:

Out-migration
In-migration
International migration
Temporary migration

The correct answer is: a) Out-migration.

Out-migration is the movement of people away from a particular place. It is often caused by factors such as limited economic opportunities, frequent droughts, and political instability. People who out-migrate are often looking for better opportunities in other places.

In-migration is the movement of people into a particular place. It is often caused by factors such as economic opportunities, job availability, and a better quality of life. People who in-migrate are often looking for a better life for themselves and their families.

International migration is the movement of people from one country to another. It is often caused by factors such as war, political instability, and economic opportunities. People who international migrate are often looking for a better life for themselves and their families.

Temporary migration is the movement of people from one place to another for a short period of time. It is often caused by factors such as work, education, and family reasons. People who temporary migrate are often looking for a better opportunity in another place for a short period of time.

In the case of districts with limited economic opportunities and frequent droughts, people are likely to out-migrate in search of better opportunities in other places.