Answer:
The most similar word to how fancy is used in this excerpt is the second one: believe.
Step-by-step explanation:
The word fancy has more than one meaning, and we can realize which one is being used by reading the context and understanding the concept. In this excerpt given, the word fancy is used by the speaker as synonyms of assumption, supposition, guess. All of these are similar to believe and that is why I chose the second option.