Final answer:
In the case of Gertz v. Robert Welch Inc., the Supreme Court determined that states cannot impose libel liability without proof of fault, which for public officials translates to 'actual malice'. Private individuals are not held to this stringent standard.
Step-by-step explanation:
The Supreme Court limited state libel law in Gertz v. Robert Welch Inc. by ruling that states may not impose liability without proof of fault. However, when it comes to private individuals who are libel plaintiffs, the standards are different. Based on the provided information and pertinent Supreme Court rulings, the correct answers to the terms in the question would be: a) Malice; actual malice, because the Court ruled that there has to be proof of 'actual malice' when the plaintiff is a public official. 'Actual malice' means the statement was made with knowledge that it was false or with reckless disregard of whether it was false or not.
States do not have to require private individuals to prove 'actual malice'. Essentially, public officials have to meet a higher standard of proof because of the important role that open debate plays in a democratic society.