Black bravely goes after the knight. There is a price to pay: the king is weakened.
1. c2c4  1... g8f6  2. b1c3  2... e7e5  3. g1f3  3... b8c6  4. g2g3  4... f8b4  5. f1g2  5... e8g8  6. c3d5  6... e5e4 This is considered the best reply according to theory, although other moves are possible. 7. f3h4  7... d7d6  8. e1g1 