Through which routes can regular insulin be administered?

Regular insulin can be administered through both subcutaneous and intravenous routes, making the choice of subcutaneous and intravenous the correct answer.

Subcutaneous administration is the most common method for insulin delivery, often used for routine management of diabetes in which insulin is injected into the fatty tissue just beneath the skin. This allows for a slow and steady absorption of the insulin into the bloodstream.

The intravenous route is typically reserved for situations that require a rapid response, such as in hospital settings for patients with diabetic ketoacidosis or hyperglycemic emergencies. Intravenous administration allows for immediate effects and precise control of blood glucose levels.

Other options, such as oral administration, are not suitable for regular insulin because peptides, like insulin, would be destroyed in the gastrointestinal tract before they could enter the bloodstream and exert their intended effects. Therefore, the combination of subcutaneous and intravenous options best captures the routes through which regular insulin can be effectively administered.