Final answer:
Food handlers are typically allowed to wear a plain band, such as a smooth wedding ring, on their hands while working to maintain hygiene and prevent contamination. Option a is correct.
Step-by-step explanation:
The type of jewelry that can be worn on a food handler's hand or arm is a plain band, such as a wedding ring with no stones, engravings, or crevices that can harbor bacteria and potentially contaminate food.
In most food service environments, regulations typically prohibit food handlers from wearing other forms of jewelry like watches, bracelets, or rings with stones because they can easily collect food particles and bacteria, posing a hygiene risk.