Darius participated in a study of the effects of alcohol on long-term memory. More than a year after his participation ended, he received a newsletter telling him all about the results of the study. The researchers were following the ethical guideline that mandates

The researchers were following the ethical guideline that mandates knowledge of results.

Explanation:

Alcohol obstructs the storage ability of the brain. Alcohol influences information transfer from short-term memory to long-term storage. Hippocampus is a part of the brain which is mainly affected due to heavy drinking of alcohol. Hippocampus shrinks and reduces the size of brain cells.

Excessive drinking destroys brain tissue and can lead to several types of memory loss. Alcohol has immense effects on teens comparing to adults. Consumption of alcohol may lead to memory loss in teens.