Final answer:
The denominator for calculating the C-section rate is the number of women who delivered, which is 263.
Step-by-step explanation:
The correct denominator for calculating the C-section rate is B. "Number of women who delivered." The C-section rate is typically expressed as a percentage of C-section deliveries among total deliveries. In this case, the denominator should include all women who completed the delivery process, whether through C-section or vaginal birth.
Therefore, the relevant figure is the total number of women who delivered, which ensures an accurate representation of the proportion of C-sections in relation to overall deliveries and aids in assessing the prevalence of this surgical procedure within the Obstetrics service during the specified period.