From the given options, select the Figure of Speech (Poetic Device) used in the expression:

"All the world is a stage” 

The correct answer is Metaphor.

Key Points

• The figure of speech used in the expression "All the world is a stage" is a metaphor.
• A metaphor is a figure of speech that compares two things without using the words "like" or "as".
• In this case, the world is being compared to a stage, implying that life is like a play, with people playing different roles and going through different stages.
• The metaphor helps to create a vivid image in the reader's mind and adds depth and meaning to the expression.
• Thus, option 4 is the correct answer.