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5…c5 before castling: the Bb5+ check
Same line, but Black plays 5…c5 before castling. You answer 6.c3 7 times out of 9, and your file puts the cost at 6.6 points of winning chances each time. The right move is 6.Bb5+.
Review: after 7…Qc7 8.Nd2 Nbd7, which move holds e5?