Generally, a travelogue provides a place to preserve memories, provide a purpose for travel, and offer a connection with local communities. The main purposes of a travelogue though are to inform readers about a place, landscape or culture.  A travelogue is a truthful account of an individual's experiences traveling, usually written in the past tense and in the first person.
It's meant to inform and explain.
 
        
             
        
        
        
This section refines and serves the author’s purpose because It lets the reader know that the authors are going to describe how honey relates to the story of sugar. This book is about the history of sugar and the changes and consequences that sugar brought to  humanity.
 
        
             
        
        
        
Well I have never heard of this book but from the sound of it I believe the answer would be B. However I could be wrong.  <span />