Chess Opening Theory/1. e4/1...e5/2. d4/2...exd4/3. c3/3...dxc3/4. Bc4/4...cxb2/5. Bxb2/5...Nf6/6. e5/6...d5/7. exf6/7...Bb4

= Danish Gambit Accepted, Classical Defence =

7...Bb4
White has five legal moves to respond to the check. Ke2 is not the right one.

8. Kf1 is surprisingly popular, but the positive of keeping lines open is outweighed by the negative of losing castling rights,  especially since the h1-rook can't get out via h3 while Black's unopposed light-squared bishop is watching it.

8. Nc3 looks natural, but 8...Qxf6! is a very cold shower. Far from stepping into a discovered attack, Black is setting up a devastating cross-pin on the knight that White must waste several moves wriggling out of.

8. Nd2 means it's White, not Black, who will lose castling rights after 8...dxc4. Thanks to the threatened pawn fork on c3, White won't have time to reinforce d2 with Ngf3.

So by a process of elimination we have 8. Bc3. This time there's a tactical flaw with 8...Qxf6, so Black must exchange bishops on c3 so as not to lose a piece.