Explanation:

- Expressly or impliedly: An agency is created either by a clear, direct agreement (expressly) or through actions or circumstances where authority is assumed (impliedly).

- Necessity: An agency arises by necessity in situations where one has to act on behalf of another to prevent harm or loss, often without explicit agreement.

- Ratification: This occurs when someone acts on behalf of another without permission, but the principal later accepts or confirms the act, creating an agency relationship retrospectively.

- All the above: Agencies can indeed be created through all of the above methods.

Correct Answer: Option 4 - All the above