There is flexibility in which of <hint>, <answer>, and <solution> may be included or excluded. You can choose to author these or not, and then decide which to include in the student version, and which to include in an independently produced instructor version.
Issued to Charles Darwin.  Do Not Copy.
It would be a trivial technical exercise to remove this, but perhaps the moral imperative (in an extra <preface>?) would dissuade most?