Translate the following English sentence to French:
"The Commission must guarantee that those directives are transposed into national law correctly and, clearly, to monitor all the issues relating to its application, which is the responsibility of the national authorities."
La Commission doit garantir que lesdites directives soient correctement transposées dans les législations nationales et, évidemment, que toutes les questions relatives à leur application soient suivies, ce qui est du ressort des autorités nationales.