Answer: D. Juliet takes the potion.
Explanation: The event that happens last in "Romeo and Juliet" by William Shakespeare is D. Juliet takes the potion. The events happen as follows: A. Tybalt fights with Mercutio. Mercutio dies. Romeo fights Tybalt and kills him. C. Romeo leaves Verona. The Prince has ordered him to leave the city after he killed Tybalt. B. Paris meets Juliet at Friar Laurence's cell. D. Juliet takes the potion to avoid having to marry Paris.