from an ethical stance, researchers should choose topics of study that
o may be researched quickly
o may be researched inexpensively
o can all people live better lives
o are politically correct

I believe the answer is the third option. Simply because a topic can be studied quickly or inexpensively doesn’t mean that it is ethical. Topics of study that are politically correct may be seen as ethical for some, but not to others, while a topic that will improve the lives of many would be seen as ethical by the general population.