Collecting maps can be an enjoyable hobby for antiquarian booksellers, a captivating interest for cartographers, a lucrative vocation for astute dealers
What is the main idea of the passage?
A. Why hobbyists always flaunt their map collections.
B. How maps can be collected by professionals and enthusiasts.
C. How to assure an interrupted flow of collectibles.
D. What cartographers advocate as a worthy undertaking.