Hartzell Inc. had the following data for 2020, in millions: Net income = $600; after-tax operating income [EBIT(1 - T)] = $700; and Total assets = $1,900. Information for 2021 is as follows: Net income = $825; after-tax operating income [EBIT(1 - T)] = $1,550; and Total assets = $2,600. Assume the firm had no excess cash. How much free cash flow did the firm generate during 2021?

a. $125 million

b. $2,250 million

c. $1,325 million

d. $850 million

e. $1,525 million