Which description accurately contrasts pens and vials for delivering medications?

• A. Pens are pre-filled auto-injectors and vials require manual drawing of medication with a syringe.
• B. Vials are pre-filled auto-injectors and pens require manual drawing.
• C. Pens and vials differ only in color; both require syringe drawing.
• D. Vials deliver medication automatically; pens require manual drawing.

Answer: (A)

Understanding how the dose is prepared and delivered is the key. Pens are pre-filled devices that act as auto-injectors; you activate them and the device automatically delivers a fixed dose through an integrated needle. Vials contain medication that isn’t pre-measured, so to administer you attach a syringe, insert it into the vial’s stopper, and draw up the required amount before injecting. This contrast captures why the description is correct: one device provides ready-to-use, automatic dosing, while the other requires manual drawing to measure the dose. The other statements misstate how either device works (for example, calling vials auto-injectors, or saying both require drawing, or claiming only a color difference).