Answer: 2. It is likely that a confounding variable could be a contributing explanation for the difference between these two groups.
3. This is an observational study, not an experiment.
Step-by-step explanation:
Based on the information given, the statement that's true include:
• It is likely that a confounding variable could be a contributing explanation for the difference between these two groups.
• This is an observational study, not an experiment.
It is an observational study as the researcher observed just observed the scenarios without him trying to change the people that are being exposed to it or controlling it.
Therefore, the correct options are II and III only.