The book is on the table.

Explanation:
- This question is testing the understanding of prepositions.
- Prepositions are words that show the relationship between a noun or pronoun and other words in a sentence.
- In this sentence, the preposition "on" is used to show the relationship between the book and the table.
- The preposition "on" indicates that the book is physically located on top of the table.
- Let's analyze the other options to understand why they are incorrect:

a) "On" - Correct Answer:
- The preposition "on" is used to indicate that one thing is physically located on top of another.
- In this sentence, the book is physically located on the table, so the correct preposition to use is "on".

b) "In" - Incorrect Answer:
- The preposition "in" is used to indicate that something is inside or within something else.
- Using "in" in this sentence would imply that the book is inside the table, which is not the intended meaning.

c) "At" - Incorrect Answer:
- The preposition "at" is used to indicate a specific location or position.
- Using "at" in this sentence would imply that the book is positioned at the table, but not necessarily on top of it.

d) "Over" - Incorrect Answer:
- The preposition "over" is used to indicate that one thing is physically positioned above or higher than another.
- Using "over" in this sentence would imply that the book is positioned above the table, but not necessarily on top of it.

Conclusion:
- The correct preposition to use in this sentence is "on" because it accurately conveys the relationship between the book and the table, indicating that the book is physically located on top of the table.