On the informative media poster "U R What U Eat," the colors green, yellow, and red correspond to the Go, Slow, and Whoa food categories.

Which best explains the author's use of metaphor with regards to this coloring system?

A. The colors suggest the coloration of a rainbow.

B. These colors are associated with healthy foods like fruit and vegetables.

C. These colors are associated with controlling the flow of traffic.

D. These colors are associated with positive and negative emotions.