Which of the following is not a statement?

Explanation:

• A sentence that asserts the truth of something is known as a statement.
• The sentences given in the first three options are statements as they deliver facts.
• “Every set is a finite set.”, “Every square is a rectangle.”, “The sun is a star.” are all statements.
• But, the sentence, “Shut the window.” does not deliver any facts and it is an imperative sentence giving an instruction to shut the window.

Hence, it is not a statement.

Final answer: The correct option is D, i.e. Shut the window.