Which of the following best defines computer crime?

The definition of computer crime encompasses illegal acts specifically involving a computer as a tool or instrument to commit these offenses. This includes a wide range of criminal activities such as identity theft, phishing, cyberbullying, and spreading malware, which can all be executed using computers or similar devices.

The term "computer crime" implies that the computer is not just a target but is actively used to facilitate the criminal act, which aligns with the broader spectrum of crimes taking place in the digital space. This definition recognizes the integral role that technology plays in contemporary criminal behavior, which is why option B is the most comprehensive and accurate choice.

In contrast, other options are more limited in their scope or do not adequately capture the essence of computer crime itself. For instance, violations of workplace policies may involve computers but do not necessarily involve criminal behavior. Similarly, hacking into secure networks is a specific type of computer crime but is not representative of all illegal activities involving computers. Lastly, physical theft of computer equipment refers to traditional theft and does not involve the misuse of computers in executing illegal acts. Thus, the best choice defining computer crime is option B.