Which term denotes an inactive substance used as a control?

• A. Gtt.
• B. Placebo
• C. Inhaler
• D. Suspension

Answer: (B)

An inactive substance used as a control is called a placebo. The main idea is to provide a treatment that looks and is administered the same as the real drug but contains no active ingredient, so researchers can see whether observed effects are due to the drug itself or to placebo effects, expectations, or other factors. This helps establish a true comparison baseline and supports blinding to reduce bias. The other terms refer to different concepts: drops (dosage form), a device for delivering medication, and a liquid formulation with suspended particles, none of which denote an inert control.