We vote for the members of Congress to represent us. What principle is this? A. federalism
B. Republicanism
C. Limited government
D. elections

A. This is best described as an observational study.

B. The explanatory variable is the amount of caffeine consumed.

E. The response variable is the score on the computer-based memory test

Explanation:

A. Observational study can be defined as the way a person or people are observe.

The observational study often attempt to understand the relationship between the cause and effect in order to help measure certain outcomes. According to the case study the incident is best described as an OBSERVATIONAL STUDY

B.An explanatory variable can be defined as the variable that are not dependent in which another variable cannot affect it.

And this independent variable can often be used to help analyse the effect on another variable which is why the EXPLORATORY STUDY is the amount of caffeine consumed.

C. Response Variable can be defined as the variable which depend on other variables and this response variables help to provide the result or outcomes that will be used as the evidence of the effect of the caffeine

Which is why the RESPONSE VARIABLE is the score of the computer based memory test which will serve as the evidence of the effect of caffeine and it effect on their scores which is why their scores were compared with how much caffeine they consumed that week.