Final answer:
The correct option for the formal affirmative command is O Beba agua.
Step-by-step explanation:
The correct option to select the formal affirmative command is O Beba agua. The other options are not correct because they use the informal affirmative command instead of the formal affirmative command. For example, Cubre la cabeza is the informal command form, while Cubra la cabeza would be the formal command form. The formal affirmative command is used when speaking to someone with whom you have a formal or respectful relationship.
Learn more about Formal affirmative command in Spanish