Relational is the best type of research study for placing objects into categories.
Answer: Option B
Explanation:
Categorization is the process of making a set of objects having similar properties under a single category. The research study can be classified as quantitative, qualitative and descriptive types.
The categorisation is based on the qualitative research under the sub type of relation or classification research. Based on the relation between each objects, they will be grouped together.
If two or more objects have any kind of positive relations like similar behaviours, they will be grouped together and if their properties are different then the objects will be placed in different groups.