Using the below what is the best suited identification strategy?

Research question - Does exposure to violent video games lead to an increase in aggressive behavior among adolescents?

-For this study, the population of interest is all adolescents in America. The sampling frame is a list of all registered American university undergraduate students. The sample is students who play violent video games. The unit of analysis will be the individual adolescent. The experiment will be conducted at the university level with the permission of the university administration. It will comprise all students. The students will be divided into two groups. The first group will be assigned to play the violent video game Mortal Kombat, and the second group will play the non-violent video game Mario Kart. After playing the game for 30 minutes, the participants will complete a survey that will measure their feelings - each question will have a 1 to 5 scale, with 1 feeling the lowest and 5 feeling the highest. After playing the assigned game, the questions are put in place to see where their aggression levels are. By accounting for all registered undergraduate university students in America, this research will observe a large sample to identify if the duration of playing violent video games increases aggressive behavior.

-The dependent variable is aggressive behavior among adolescents, measured in CIS scoring. The CIS involves a 1-5 scale that will evaluate aggressive behavior, thoughts, and emotions. The lower the number the less irritability anf the higher the number the more likely a person is aggressive.

-The independent variable is exposure to violent video game, which is measured in how long they play the game for.