Final answer:
According to USP 797 guidelines, d)gloves should be donned last before starting the compounding process to maintain sterility and prevent contamination.
Step-by-step explanation:
According to USP 797, which is a set of guidelines issued by the United States Pharmacopeia for compounding sterile preparations, the item that should be donned last before you start compounding is gloves.
The order of donning personal protective equipment (PPE) is critical to maintaining sterility and preventing contamination in compounding areas.
The general sequence recommended includes starting with foundational items like gowns and then moving on to more critical barriers of protection such as gloves which have direct contact with sterile products. Therefore, the correct answer is d) Gloves.