Tibbs Inc. had the following data for the year ending 12/31/07: Net income = $300; Net operating profit after taxes (NOPAT) = $400; Total assets = $2,500; Short-term investments = $200; Stockholders' equity = $1,800; Total debt = $700; and Total operating capital = $2,300. What was its return on invested capital (ROIC)?
a. 14.91%
b. 15.70%
c. 16.52%
d. 17.39%
e. 18.26%