How might handler experience influence rodent study outcomes and how can this be controlled?

How might handler experience influence rodent study outcomes and how can this be controlled?

• A. Handler skill has no effect.
• B. Only automated systems matter.
• C. Dosing accuracy is unaffected by handler.
• D. Handler skill can influence stress, dosing accuracy, and measurement; control by standardized training, randomization, and blinding where feasible.

Answer: (D)