Final answer:
Henry III of the House of Valois had Henry de Guise assassinated during the War of the Three Henries and later named Henry of Navarre as his heir to the French throne.
Step-by-step explanation:
The correct answer to the question is D) Henry III. This French king was indeed the favorite son of Catherine de Medici. During the War of the Three Henries, which was a struggle for control over France among Henry III, Henry of Guise, and Henry of Navarre, Henry III ordered the assassination of Henry de Guise. After Henry III himself was mortally wounded by an assassin, he named Henry of Navarre as his heir. Henry of Navarre, a Protestant, ascended to the French throne as Henry IV and later converted to Catholicism, ultimately issuing the Edict of Nantes which granted religious tolerance to Huguenots and thus established domestic tranquility and stability after a period of religious and civil wars in France.