Which of the following is a component of a syringe?

• A. Cap
• B. Stopper
• C. Plunger
• D. Needle cover

Answer: (C)

The moving part that enables drawing in and delivering liquid is the plunger. It fits inside the barrel like a piston, and as you pull it back, it increases the internal volume and lowers pressure to draw fluid into the syringe. Pushing it forward decreases the volume and forces the liquid out through the needle. The seal at the end of the plunger (often called a stopper) is part of this plunger assembly and helps maintain a tight seal for proper suction and expulsion, but the basic operating component you interact with to administer medication is the plunger. Cap and needle cover are protective accessories used to keep the needle sterile before use, not the functional parts that move the liquid.