What is a key point? Like a key point of a novel. Would it be a main idea??

In large cities such as new york city, a majority of citizens often take public transportation and leave their cars at home what is wrong with this text and visual aid

Drag the tiles to the boxes to form correct pairs. match each excerpt to the type of characterization it uses.

Which sentence is punctuated correctly?  a.under a microscope; the organisms look a bit like ruffled tennis balls they have armored plates that fit together to make a round shape. b.when the water is disturbed; the organisms respond by glowing this makes swimmers look like floating beams of blue light. c.there is a bay in puerto rico that seems to light up at night; the light comes from tiny organisms in the water. d.the luminescence attracts visitors from around the world people are curious to see; this beautiful otherworldly sight.