A technical decision. The position of the Bd4 is undermined, and the pawn on b7 becomes backward.

Black’s only means of getting activity.

27...fxe4 28.Qxd4 Qxh3+ 29.gxh3 cxd4 30.d6!+– – the passed pawn marches to d7, whilst the black pawns, unsupported by pieces, are going nowhere.

Losing at once. More tenacious was 30...b4, but after, for example, 31.Rf3±, White can put his rook on d3 and bring his king to f3, when, in time, the central passed pawns should decide the game in White’s favor.

The strongest and most energetic, not losing a single tempo!

18...exf5 19.e6 Rg8 20.exf7+ Kxf7 21.Bg2, with a strong attack.
18...Qc7 19.fxe6 Bxe6 (19...fxe6 20.Nf6+ Kd8 21.Nxd5 exd5 22.Qxd5+ Ke8 23.Bc4 Rf8 24.Rhf1+–) 20.Ng7+ Kd7 21.Nxe6 fxe6 22.Qxg4 Qc6 23.Bh3, with the initiative.

Now, the threat of a sacrifice on d5 hangs over Black.

23...Rxf5 24.Bxe6 Qxd4 25.Bxf5++–.

The d6-pawn is Black’s main problem. But to press on it conveniently, White needs to secure some space on the light squares, and this task is achieved by...