The Bank of Loans uses the following rating scheme to classify the riskiness of its customers. Risk Premium (%) Risk Class Prime High grade Upper medium grade Lower medium grade Speculative: Non-investment grade Speculative: Highly Substantial risks Extremely speculative 12.0 The bank's pure rate of interest is 1.5% and the inflation premium is 3%. What rate would the bank offer a customer who is in the upper medium grade risk class? A.8.20% B. 6.11% C.-8.73% D. 6.64% E. 7.68% F. 7.16%