Generating Borel measurable mappings with continuous mappings

We prove that the relative rank r(B(X):C(X)) of the semigroup of Borel mappings B(X) from X to X (with the composition of mappings as the semigroup operation) with respect to the semigroup of continuous functions C(X) from X to X is equal to ℵ1 if X is an uncountable Polish space which either can be retracted to a Cantor subset of X, or contains an arc, or is homeomorphic to its Cartesian square X2.