The process of focusing on only the most important factors to explain a phenomenon is called a. controlled experimentation. b. marginal analysis. c. the trade-off between efficiency and equality. d. abstraction. e. rational choice.

d. abstraction.

Explanation:

Abstraction: In psychology, the term abstraction is defined as one of the thinking processes that tend to reduce a piece of particular information's content related to a specific concept to retain only those information which is considered as relevant for a particular purpose or requirement.

Example: An individual's feelings of happiness and sadness.

In the question above, the given statement signifies the abstraction.