While walking through the mall, joe witnessed a large group of what seemed like regular shoppers simultaneously drop their bags and perform a synchronized dance, after which each person picked up his or her belongings and walked off like nothing had happened. joe witnessed?

Lol, that would be a flash mob. Here's the definition.

flash mobnouna large public gathering at which people perform an unusual or seemingly random act and then disperse, typically organized by means of the Internet or social media.
(Credit to google) (https://www.google.com/search?ei=kl0GW6i9HoK-0PEPj-eAyAs&q=what+is+a+flash+mob&oq=what+is+a+flash+mo...)

Where is the map? explain the choices?