Susan purchased 20 shares of X stock in 2010 for $20 per share. Susan purchased an additional 20 shares of X stock in 2015 for $40 per share. Susan purchased an additional 20 shares of X stock in 2019 for $35 per share. Susan does not keep the shares in separate accounts and cannot determine which share was purchased at any given time. In 2022 Susan sold 30 shares of X stock for $50 per share ($1,500). What is Susan's gain recognized on the sale in 2020? a. $1,500 b. $700 c. $350 d. $0 e. None of a