Which cocktail includes Raspberry Liqueur as an ingredient?

The French Martini is a cocktail that prominently features Raspberry Liqueur, typically Chambord. This liqueur adds a rich berry flavor and sweetness that complements the other ingredients, which usually include vodka and pineapple juice. The combination results in a fruity and refreshing drink that has gained popularity for its vibrant hue and appealing taste.

In contrast, the other cocktails mentioned do not typically include Raspberry Liqueur. The Watermelon Martini focuses on fresh watermelon pureé or juice, the Gibson is a gin martini garnished with a pickled onion, and the Chocolate Martini is primarily a dessert cocktail made with chocolate liqueur and vodka. Thus, the unique inclusion of Raspberry Liqueur in the French Martini makes it the correct answer.