Final answer:
In the case of Greg's construction business, Chuck, who is offering his help for free on weekends, would be best described as a Volunteer Worker according to Greg's CGL policy.
Step-by-step explanation:
The scenario describes Chuck as offering to help Greg in his construction business on weekends without pay to gain experience. In the context of Greg's Commercial General Liability (CGL) policy, the best description of Chuck would be as a Volunteer Worker. This is because Chuck is neither employed nor contracted for wages by Greg, which eliminates the possibilities of being a leased, part-time, or temporary worker. Chuck's situation is akin to unpaid internships or scenarios where individuals volunteer their services to gain experience or for other personal reasons.