Which of the following is a valid transformation (one step) from the unification problem unify({g(a,b,c) = g(a, x,B), a = x})? Variables are represented by Greek letters. a = (a) None of these are correct. (b) unify({a = a, ß = x,c= B, a = x}) (c) unify({a = a, ß = x,c= B}) (d) unify({a = x}) (e) unify({a = x,g=g}) - =