What service related to the pecan pumpcake involves a zig-zag pattern?

The service related to the pecan pumpcake that involves a zig-zag pattern is the pecan sauce. When serving dishes like the pecan pumpcake, creating a zig-zag design with the sauce adds visual appeal and enhances the presentation of the dish. It showcases the chef's attention to detail and elevates the dining experience, making the dish look more enticing to customers. This technique is common in restaurant plating to transform a simple dish into a more gourmet offering.

In contrast, while cream topping, chocolate drizzle, and fruit garnishes are also used to enhance desserts, they do not specifically have the characteristic zig-zag application that the pecan sauce does. Each of those options can be used for decoration but typically follow different plating styles. Pecan sauce is unique in this context for utilizing a zig-zag motif, making it the clear choice.