Answer:
The correct answer is letter "D": Preferred stock at 6.0%.
Explanation:
After-Tax Return is the revenue companies earn after the tax deduction according to the bracket they fall into. It expresses the firm's real earnings ad can be expressed in ratios (percentages). Calculating the after-tax return implies considering all the profits an organization had within a period and all its costs.
In the example:
Then, the highest after-tax return is provided by investing in preferred stocks at 6.0%.