Necessary Assumption Practice Test

Researchers found that people who drink green tea daily have a lower risk of developing heart disease. Therefore, drinking green tea is a key factor in reducing the risk of heart disease. Which one of the following assumptions is required by the argument?

A coffee chain tested a new training program in ten stores and found that customer complaints dropped by about 20% over the next month. In those same stores, managers reported that employees began greeting customers more consistently, a behavior the training emphasized. Because consistent greetings make customers feel acknowledged, the training program is what reduced complaints. So the chain should roll out the program companywide to reduce customer complaints across all its stores.