Explanation:

- Option 1: It is concerned with interstate regulation.

- This means that public international law primarily deals with laws that govern how states interact with each other.

- Option 2: It deals in regulating the conduct of one state with another.

- Public international law establishes rules for diplomatic, trade, and political interactions between countries.

- Option 3: It provides a framework of rules and regulations which help in fostering stable and organized international relations.

- This highlights the role of public international law in creating an orderly method for states to coexist peacefully and solve disputes.

- Option 4: All of the above.

- Public international law embodies all aspects mentioned in options 1, 2, and 3, as it governs state affairs, regulates interactions among states, and establishes a framework for international order.