Final answer:
The most appropriate command form of the verb is 've'.
Step-by-step explanation:
In this case, the most appropriate command form of the verb to fill in the blank is ve. The command form of the verb ver (to see) in second person singular is ve. So, the correct sentence would be: "Papá le dice a Pedrito: '¡Ve a tu dormitorio inmediatamente!'
Learn more about the command form of the verb