3...f5 is an important option for Black, since 4.f3 is well met by 4...e5!, with some advantage for Black. Instead White does better to prevent ...e5 with 4.Bf4, and then obtain compensation for a pawn with a subsequent f3. 3...Bf5 is well met by 4.f3, and if 4...exf3 then 5.Qxf3 attacking the bishop (thus Black may be better off transposing to the Vienna Defence with 4...Nf6). 3...c6 and 3...e6 transpose to the Caro–Kann Defence and French Defence respectively, and in the former case White can continue in Blackmar–Diemer Gambit style with 4.f3 or 4.Bc4 intending 5.f3 (which often transposes to the O'Kelly Defence). After 3...e6, however, White cannot easily force a Blackmar–Diemer Gambit type position as 4.f3 Bb4 (which also comes up via the French Rubinstein Variation) is very bad for White.