Answer:
A. $900
Explanation:
Section 351 states that no gain or loss shall be recognized if property is transferred to a corporation by one or more persons solely in exchange for stock in such corporation and immediately after the exchange such person or persons are in control (as defined in section 368(c)) of the corporation. Therefore, Rachelle's tax basis in the stock received in the exchange equals to the sum of the stock's fair market value of $750, $50 in cash, and the liability of $100 that the corporation credited into their book.