Final answer:
Remifentanil is the best option for a drug with a predictable and fast offset due to its unique metabolism which results in an ultra-short half-life.
Step-by-step explanation:
The predictable and fast offset of a drug refers to how quickly and reliably a drug's effects decrease after it is discontinued. Among the options provided (Fentanyl, Alfentanil, Sufentanil, Remifentanil), the best drug for a predictable and fast offset is Remifentanil. This is due to its unique metabolism through plasma esterases, which allows for rapid elimination from the body regardless of the duration of infusion. As a result, Remifentanil has an ultra-short half-life and its effects dissipate quickly once the infusion is stopped, providing a predictable offset.