Staffing for each type of service vary depending upon the menu and level of service required

Staffing for each type of service vary depending upon the menu and level of service required. Which staffing ratio is recommended for wait staff for sit-down service?

Staffing for each type of service vary depending upon the menu and level of service required. Which staffing ratio is recommended for wait staff for sit down service?
a. 1 per 8-10 guests
b. 1 per 40-50 guests
c. 1 per 10-15 guests
d. 1 per 20-30 guests
e. 1 per 30-40 guests