计算:7-(-4)=(    )

An analyst gathered the following information for a company:
Risk-free rate = 6.75%
Expected market return = 15.00%
Beta = 1.30
Dividend payout ratio = 55%
Profit margin = 10.0%
Total asset turnover = 0.75
Assets to equity ratio = 2.00
What is the firm's sustainable growth rate（）

A. Tax rate needed to determine answer.

B. 6.75%.

C. 15.00%.