You are requested to keep the book on the table.

The correct answer is D. Please keep the book on the table.

The other options are incorrect because they do not convey the same level of politeness or urgency.

• Option A, “You should keep the book on the table,” is a suggestion, not a request. It is up to the listener to decide whether or not to follow the suggestion.
• Option B, “You must keep the book on the table,” is a command, not a request. It is not polite to give someone a command, unless they are your child or employee.
• Option C, “Please kept the book on the table,” is grammatically incorrect. The correct way to say this would be “Please keep the book on the table.”

In conclusion, the correct answer is D. Please keep the book on the table. This option is polite and conveys the urgency of the request.