What do naturalistic observation,case studies,and surveys all have in common

A)  They can show causal relationships. 
B)  The results obtained cannot be analyzed statistically. 
C)  They do not directly observe behaviour. 
D)  They do not manipulate the variables under study.

Naturalistic Observation

A research method involving observing subjects in their natural environment without intervention by the researchers.

Case Studies

Research methods involving the detailed examination of a single example or case.

Surveys

Research methods involving the collection of data from a predefined group of respondents to gain information and insights on various topics of interest.