Final answer:
The 16-hour elapsed time rule for federally regulated drivers includes all on-duty time but excludes off-duty rest or break time.
Step-by-step explanation:
The 16-hour elapsed time rule for federally regulated drivers refers to the maximum amount of time a commercial motor vehicle (CMV) driver can be on-duty during a work shift before they are required to take a 10-hour off-duty period. Specifically, the rule states that a driver can be on-duty for up to 16 hours following 10 consecutive hours off-duty. This 16-hour period includes all driving time and any additional on-duty time, but does not include rest or break time, assuming those breaks are off-duty time. Therefore, the answer is b) On-duty time.