Which text represents an algorithm?

An algorithm is a step-by-step procedure or a set of instructions that are designed to perform a specific task or solve a problem. The best representation of an algorithm among the provided options is the choice that outlines clear, sequential actions.

The selected text outlines a series of actions to unlock a door: inserting the key, turning it, and opening the door. Each of these steps is essential and must be performed in the specified order to achieve the desired outcome, which is to open the door. This demonstrates the key characteristics of an algorithm: a clear sequence of operations aimed at accomplishing a task.

In contrast, the other options do not describe sequences of actions or procedures. The first option merely states a fact about animals having tails without any action involved. The third option provides a weather forecast, which is informational rather than prescriptive. The fourth option describes the contents of a box but does not imply any steps or procedures to be followed. Hence, only the selected text represents an algorithm that includes actionable steps.