Crossover Study is best described as which of the following?

• A. Placebo
• B. Phase III Testing
• C. Crossover Study
• D. IND

Answer: (C)

A crossover study centers on giving each participant multiple treatments in a random sequence and comparing their effects within the same person. Because every participant experiences all interventions, natural differences between individuals don’t cloud the comparison, increasing the study’s sensitivity to detect true differences between treatments. A washout period between treatments helps prevent one treatment’s effects from carrying over into the next.

This design works best when the condition is stable and the treatment effects are reversible, so you can directly see how each treatment compares within the same patient. The other terms refer to different concepts: a placebo is just an inactive control, Phase III testing is a later-stage clinical trial focused on broad efficacy and safety, and IND is a regulatory filing to start human trials.