Final answer:
The estimated due date based on Naegele's Rule for a last menstrual period that began on May 21, 2016, would be February 28, 2017.
Step-by-step explanation:
Based on the Naegele's Rule, which is used to estimate the due date of a baby, you would take the first day of the last menstrual period (LMP), add one year, subtract three months, and add seven days. For a last menstrual period beginning on May 21, 2016, the estimated due date would be:
- Add one year: May 21, 2017
- Subtract three months: February 21, 2017
- Add seven days: February 28, 2017
Therefore, the estimated due date would be February 28, 2017.