$(14)$ Which of the following is NOT part of the return on assets?

a$.$ percent of sales that represent a company's earnings

b$.$ dollars of sales generated per dollar of assets

c$.$ level of leverage that a firm is taking

d$.$ dollars of net income generated per dollar of equities

e$.$ All of the above are part of the return on assets.

f$.$ Neither c nor d is part of the return on assets.