Right answer: Yo pondré el libro en la mesa.
In Spanish (Castilian) the future tense is used to talk about what will happen or shall happen,it is also used to express wonder or probability in some cases.
In this context, the following sentence is written with the verb poner (to put) and the first person in singular Yo (I).
Note in spanish the conjugation of a verb must be in accordance with the subject, therefore the correct future tense form of this verb is pondré (I will put):
Yo pondré el libro en la mesa.
I will put the book on the table.