Which was not a result of increased population growth in the region? brain drain decreased petroleum production increased competition for jobs increased membership in extremist groups

The correct answer is - brain drain.

The brain drain process is a process that appears when the population is declining through migration. With a migration in which mostly the younger population that has higher education is leaving to live in other places, the region is losing the young and prosperous minds, thus being in a process of brain drain.

With the suggested situation that the population is growing in the region, the result will for sure not be to have a brain drain process. Instead, it will be more of a situation of brain gain, as there's more and more people in the region.