explane why C is the correct answer

Parent Corporation owns 100% of the single class of stock of Subsidiary Corporation. Parent's basis in the Subsidiary stock is $500,000 when Parent completely liquidates Subsidiary Corporation within a single tax year. The Subsidiary Corporation assets have a $700,000 adjusted basis and an $800,000 FMV at liquidation. As a result of the liquidation, Parent must recognize a $200,000 gain. $300,000 gain. $0 gain. None of the above