16 0 / 1 pts On March 30, 2018, Frank bought 1,000 shares of Wolf Corporation stock at $12 per share. Two years later, the stock price started to drop. On April 15, 2020, Frank sold 500 shares at $11 per share. Two weeks later, on April 29, 2020, the stock price dropped to $10 per share and Frank bought 1,500 shares at the market price. What is Frank's basis in the Wolf stock he purchased on April 29, 2020? $18,000 $15,000 $16,500 $15,500