They just added NGOs to confuse us. point is most social research is carried out by NGO's. As for the applicability of this these types of research. Research depends on your objective. And objectives are of 4 types. Descriptive just defines an issue. explanatory gives reasons for the issue. Correlational establishes relationship between variables. exploratory is prelimenary research. Now all you had to do was describe these types. Make examples in your head and add word NGO's. Like. "an NGO undertakes a correlational research to understand whether theres a relationship between a dysfunctional family setup and drug abuse"