Toby Tells You That He Prefers Hamburgers to Hot Dogs

Toby tells you that he prefers hamburgers to hot dogs, hot dogs to tacos, and hamburgers to tacos. This violates what assumption made when analyzing consumer preferences?

A) that more is better
B) that there is a diminishing marginal rate of substitution
C) that consumers are rational
D) This does not violate any assumptions relating to consumer preference.