Final answer:
It is not a good idea to allow a friend who has been drinking alcohol to ride their motorcycle.
Step-by-step explanation:
The best option from the given choices is d. Allow your friend to ride their motorcycle.
When a person has been drinking alcohol, their ability to operate a vehicle, such as a motorcycle, is impaired. Alcohol affects a person's judgment, coordination, and reaction time, which can increase the risk of accidents and injuries. It is important to prioritize safety and prevent your friend from riding their motorcycle while under the influence of alcohol.