How does Higgins know where all the bystanders are from?

1] It is in his notebook.
2] He can tell by their dress and mannerisms.
3] He listened to their earlier conversation where they discussed it.
4] He can tell by their language use.

B as he concludes it from their fashion sense and manners

Studying history is very important so that we learn from past experiences and don't repeat the bad ideas/choices that might have been made. it can tell us how cultures conducted their lives and you can learn about interesting facts you might not know. hope this ! : )