Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...f5/4. Nc3/4...fxe4/5. Nxe4/5...d5/6. Nxe5/6...dxe4/7. Nxc6/7...Qd5/8. c4/8...Qd6/9. Nxa7
Black isn't thrilled about the prospect of trading pieces when she's two pawns down, but the c8-bishop is coming off the board regardless, so it might as well be with 9...Bd7 which preserves Black's right to castle, rather than with the tempting 9...c6 which runs into 10.Nxc8 hitting the queen.