Correct answer: Kb21...e:f3 2.d4# 1...e3 2.d:e3# 1...c:b3 2.d3# 1.R:b5?? zz 1...e:f3 2.d3#/d4# 1...e3 2.d:e3# but 1...c:b3! 1.b:c4?? zz 1...e:f3 2.d4# 1...e3 2.d:e3#/c:b5#/c5# but 1...b:c4! 1.K
