Carlsen prefers to develop first before pushing the b-pawn.
1. e2e4  1... c7c5  2. g1f3  2... d7d6  3. d2d4  3... c5d4  4. f3d4  4... g8f6  5. b1c3  5... g7g6  6. c1e3  6... f8g7  7. f2f3  7... a7a6  8. d1d2  8... h7h5  9. f1c4 