Earlier this year, you purchased $5,000 worth of an Spartan Power common stock. At the same time, your sister purchased $5,000 worth of an Badger Biolabs preferred stock with a 7% non-cumalative annual dividend at $25 per share (same price as par value). Last week the company announced it invented a new battery with double the capacity of its competitors and analysts estimate sales will rise 50% annually for the next seven years. Based on this information, which investment of the siblings has the greatest chance of earning a higher return?

a. Badger Biolabs subordinate debt

b. Impossible to estimate

c. Badger Biolabs preferred debt

d. Spartan Power common stock