Which seasonal product is known for its green color?

The Shamrock Shake is the seasonal product known for its distinct green color. This shake is typically offered by McDonald's during the St. Patrick's Day season and is characterized by its mint flavor and bright green hue, making it easily recognizable as a festive treat. The green color not only represents the holiday but also adds to the overall appeal of the shake.

In contrast, the other options do not have this specific green coloration associated with them. For example, the McFlurry comes in various flavors that are not associated with a particular color theme, the Eggnog Shake is creamy and has a traditional holiday flavor profile without a green hue, and the Mint Chocolate Sundae includes mint flavor but is predominantly a chocolate sundae topped with mint, which does not give it the same standout green appearance that the Shamrock Shake does. Thus, the Shamrock Shake distinctly represents both the season and the color associated with it.