meine Antwort ist d5 auf B21 Sicilian McDonnell Attack.
Zitat aus Sicilian Defence:
Grand Prix Attack: 2.f4
2.f4 is the Grand Prix Attack or McDonnell Attack: the latter name stems from the 14th match game played in London in 1834 between Alexander McDonnell and Charles Louis Mahé de La Bourdonnais, won by Black. According to Jeremy Silman and others, Black’s best reply is 2…d5 3.exd5 Nf6!, the Tal Gambit, which has caused the immediate 2.f4 to decline in popularity. White may decline the gambit with 3.Nc3, called the „Toilet Variation“, so named after its reputed place of invention. A less common option is 2…e6, as La Bourdonnais played against McDonnell. Players usually enter the Grand Prix Attack nowadays by playing 2.Nc3 first before continuing 3.f4. The modern main line runs 2.Nc3 Nc6 3.f4 g6 4.Nf3 Bg7. Here White can play the positional 5.Bb5, threatening to double Black’s pawns with Bxc6, or the more aggressive 5.Bc4, aiming for a kingside attack.