Which of the following categories does not include emergency usage?

The category that does not include emergency usage is prescription drugs. Prescription drugs are medications that require a healthcare professional's oversight for administration and use. They are typically used to manage chronic conditions, treat illnesses, or provide symptom relief under specific medical supervision.

While certain prescription drugs can be used in emergency situations, they are generally not categorized as emergency drugs, which are specifically designed for immediate use in life-threatening situations. Emergency drugs, on the other hand, are formulated for rapid response and often include medications such as epinephrine or nitroglycerin, which are critical in emergencies.

In contrast, first aid drugs and nonprescription drugs may be utilized in emergency situations as they can often be administered without a prescription or by individuals with basic first aid training. Nonprescription drugs, for example, might be used for pain relief or to treat minor injuries that require quick action. Thus, the correct answer highlights that the general category of prescription drugs does not inherently imply emergency usage like the others do.