Answer: Observational study.
Step-by-step explanation:
Given: Rodrigo sits at a street corner and records the number of red sports cars that are and are not speeding.
Here Rodrigo is not influencing the cars, just observing the cars and measure variables that which car is speeding and which are not. Therefore, the study done by him is observational study.
Observational study is the study where the researcher observes the subjects and measures variables, but does not influence the population .There is no manipulation by the researcher.
