Respuesta :
He did not separate his friends into different groups and he didn't apply a treatment is the correct answer because the environments and people around his friends are different. Maybe, they can multitask and he can't. The answer varies.
Answer:
He did not use a random sample, and he tried to show cause and effect with an observational study
please mark brainliest if this is correct
thanks :) Have an awesome day!
Step-by-step explanation: