Final answer:
Insulin glargine has the longest duration of action, providing up to 24-hour blood glucose control with once-daily injections, making it the most sustained insulin type among those listed.
Step-by-step explanation:
The insulin with the longest duration of action among the options provided is d. glargine. Insulin glargine is a long-acting insulin analog that has a prolonged duration of action when compared to other types of insulin. It is designed to be injected once daily to help control blood glucose levels for up to 24 hours, making it beneficial for those who require a consistent level of insulin throughout the day.