Which of the following can lead to altered enzyme activity related to drug metabolism?

Altered enzyme activity related to drug metabolism can indeed be affected by environmental factors. This includes aspects such as exposure to certain chemicals, pollutants, or dietary components that can influence the activity of drug-metabolizing enzymes in the liver. For example, substances like alcohol, tobacco smoke, and even certain foods can induce or inhibit specific cytochrome P450 enzymes, which play a critical role in the metabolism of many drugs.

While exercise frequency, sleep patterns, and age of the patient can have effects on overall health and potentially modification of drug response or disposition, environmental factors are particularly impactful in directly modifying the biochemistry of metabolic enzymes, thus affecting how drugs are processed in the body.