Which of these could be an "amicus curiae"?

“Amicus curiae” is a Latin expression meaning "friend of the court." It refers to someone who has an interest in the outcome of a pending lawsuit – but is not a party to the lawsuit -- and presents information in support of (or against) one of the parties. In many instances, the “amicus curiae” attempts to draw the court's attention to arguments or information that the parties may not have presented, such as the effects of a particular court ruling on the interests of certain third parties.

The presentation of arguments or information to the court is usually in the form of a brief. Such briefs are typically filed at the appellate level, although they also may be filed in lawsuits pending at the trial court level. Generally, an “amicus curiae” must obtain the court's permission before filing its brief, unless all of the parties consent to the filing.

Because an “amicus curiae” is not a party to the lawsuit there is no need to have standing to bring suit. Further, as a non-party, an “amicus curiae” normally does not have the rights that parties in a lawsuit have, such as the right to obtain discovery from other parties.