Fill in the blank with the correct form of the verb: Alejandro ________ en su cama.

The correct answer is “duerme.”

Explanation: In this sentence, “Alejandro” is a third-person singular subject (he), so we use the third-person singular form of the verb “dormir,” which is “duerme.” The other options do not fit grammatically: “dormimos” (we sleep) is for “nosotros,” “duermo” (I sleep) is for “yo,” and “duermes” (you sleep) is for “tú.”