The correct answer is: A) carefully observing behaviors.
A research design refers to the overall strategy chosen to integrate the different components of a study in a coherent and logical way. In this way you can be sure the research problem will be addressed in an effective way.
By doing an efficient research design you will be able to define a correct research problem, have the necesary information to say something about it as well as organize this information and specify your hypothesis. Later on you will be able to describe the data necesary for the testing of the hypothesis as well as how that data is going to be obtained. Lastly you will describe the methods used to analyse the data in order to prove or disprove your hypothesis.
As you can see B, C and D form part of an effective research design, the option A is a result of the design but not a part of it.
