Final answer:
Gloves and gowning are mandatory when compounding hazardous sterile products.
Step-by-step explanation:
The statement 'Gloves and gowning are optional when compounding hazardous sterile products' is false. When compounding hazardous sterile products, such as chemotherapy drugs or other hazardous medications, gloves and gowning are mandatory. This is to ensure the safety of the compounder and to prevent contamination of the product.