Answer:
b) naturalistic observation.
Step-by-step explanation:
Naturalistic observation is a descriptive method that carefully and thoroughly examines the behavior of individuals in an ecological context, that is, in their natural habitat. While the experimental method consisted of manipulating a variable to verify in a rigorously controlled manner the effect of this manipulation on the dependent variable, that is, it sought to establish a causal relationship between two phenomena, explaining one by the other. In the case of naturalistic observation there is no manipulation of variables because it is observation of spontaneous behavior in natural situations, under uncontrolled conditions. Based on this context, we can say that the team used naturalistic observation when studying the ups and downs of human humor, counting positive and negative words in 504 million Twitter messages from 84 countries.