On October 1 of the current year, Nancy transferred the assets of her sole proprietorship to K Corporation solely in exchange for stock. On that same day, Mary invested cash in K Corporation solely in exchange for 12% of K Corporation's outstanding stock with a par value of $ 100. What is the minimum percentage of outstanding stock Nancy must own on October 1 immediately after the asset exchange in order for the transfer of assets to be tax-free? A. 80% B. 68% C. 66.67% D. 50%