In their off months, Sanford Accountants employs five full-time accountants who each work 40 hours per week. However, during tax season, Sanford hires additional accountants to help prepare tax returns for clients. In the month of March, Sanford will need to log 3,500 labor hours to complete tax returns. How many additional accountants does Sanford need to hire? Assume March has 22 work days. A : 14 B : 15 C : 16 D : 12