Wei is writing a report. She wants to use a phrase that most strongly fits her topic. Choose the phrase that best belongs in the blank.
Scientists have known that people called the Mayans lived in Central America long, long ago. They did not know, however, how large
the Mayan cities actually were or how many people lived there.
A new tool, called LIDAR, helped scientists learn that Mayan cities in Guatemala were much bigger than anyone ever imagined. LIDAR
was used from airplanes to shoot laser lights over nearly 800 square miles of Guatemalan forest. The lights took pictures of objects buried
under the forest.
LIDAR showed that some of the objects were thousands of buildings making up cities. These
were even
connected by highways. Scientists believe that these city centers were once home to over 10 million people.
ancient cities
cities from the past
really old cities
experienced cities