Final answer:
Reduction, replacement, and refinement are ethical guidelines for using animals in research, aiming to minimize harm and find alternatives when possible.
Step-by-step explanation:
The principles of reduction, replacement, and refinement (the 3 Rs) are ethical guidelines for using animals in scientific research. The goal of these principles is to minimize the use of animals, reduce harm or suffering, and find alternatives whenever possible. Reduction involves using the fewest number of animals needed to obtain reliable results. Replacement involves replacing animals with nonliving models, invertebrates, or computer models. Refinement involves refining procedures to minimize pain and suffering.