Final answer:
A security guard must act lawfully, have reasonable grounds to believe they are under attack, and use only minimum force necessary.
Step-by-step explanation:
For the use of force to be justified, the security guard must:
- Act in the lawful execution of his duty: The security guard must be carrying out their responsibilities within the boundaries of the law.
- Have reasonable grounds to believe he is being attacked or will be and be able to justify their actions: The security guard must have a reasonable belief that they are or will be under attack, and be able to provide valid justification for their actions.
- Use only minimum force necessary: The security guard must use the least amount of force necessary to address the threat or situation at hand.
Therefore, the correct answer is D. All of the above.