The function y = x2 is transformed to y = (x + 4)2. which statement is true about the transformed function?

Here's a tool for your math toolbox:

     Wherever you see the word "per", it wants division.
     You should begin with a fraction.

       "People per square kilometer"
means
       (number of people) / (number of square kilometers) .

The problem just gave you both of those numbers.  So it's time to
polish up your pencil or your calculator and get to work dividing.

Notice that you made a mistake copying the estimated population
of China, and then, even worse than that, you didn't proofread your
question and correct the copying mistake.

            (Population) / (area) =

            (1,313,973,713 people) / (5,956,960 sq km) =

             220.6 people per square km.