When a shop visit happens, the data is validated through a panel of users who volunteer to participate in Google Opinion Rewards. How many users volunteer?

Google validates shop visit data through a panel of approximately 5 million users who volunteer to participate in Google Opinion Rewards. This large panel size ensures a robust and statistically significant sample for accurately estimating store visits. The other options (100,000, 500,000, 1 million) are incorrect because they represent significantly smaller sample sizes, which would not provide the same level of data reliability and accuracy for Google's extensive shop visit measurement.