My question involves defamation in the state of: Colorado. A colleague (A) asked another colleague (B) if they would like to hang out sometime outside of the workplace, no indicator of a date was requested. This colleague then reiterated this encounter with another colleague (C) who said this constituted sexual harassment. Colleague C proceeded to bring this to the attention of the owner of the company. When the initial colleague (B) found this out, they said it was not sexual harassment, however, colleague (A's) good name, reputation and working environment with other colleagues has been seriously slandered and created an impression that simply is not so.

Any advise for colleague (A) and his ability to regain his good name and workplace security?