Which of the following drinks is a variation of a traditional mocha?

A Skinny Mocha is a variation of a traditional mocha because it maintains the fundamental components of a mocha, which usually includes espresso, steamed milk, and chocolate syrup, but alters one or more ingredients to create a lighter version. Specifically, the Skinny Mocha replaces regular milk and syrup with lower-calorie alternatives, such as non-fat milk and sugar-free chocolate syrup. This modification allows customers who are looking for a less caloric option while still enjoying the rich chocolate and coffee flavors characteristic of a traditional mocha.

The other options listed do not share this foundational structure with the traditional mocha. A Caffè Americano is made by diluting espresso with hot water, resulting in a different flavor profile. An Espresso Macchiato consists of espresso with just a small amount of steamed milk or foam, diverging significantly from the sweeter and creamier flavors of a mocha. A Flat White, on the other hand, is primarily espresso with microfoam milk, emphasizing coffee rather than chocolate, which is central to a mocha's identity. Thus, the Skinny Mocha stands out as the only choice that represents a variation while retaining the essence of the original drink.