Direct observation is most like
A. Case studies
B. naturalistic observation
C. experimental methods
D. correlation

B) Naturalistic Observation

Explanation:

Case studies = A process or record of research in which detailed consideration is given to the development of a particular person, group, or situation over a period of time.

Naturalistic observation = Naturalistic observation is, in contrast to analog observation, a research tool in which a subject is observed in its natural habitat without any manipulation by the observer. During naturalistic observation, researchers take great care to avoid interfering with the behavior they are observing by using unobtrusive methods.  

Experimental methods = The use of controlled observations and measurements to test hypotheses.  

Correlation = The process of establishing a relationship or connection between two or more measures.

which of what? i am confused