Self doubt

Question

Consider the following statements:
S₁ : Three-address code is a linearized representation of syntax tree.
S₂ : The syntax tree not depicts the natural hierarchical structure of source programm.
Which of the following is true?

I know answer but i didn't understand the mean of S2.

Comments

http://www.allsyllabus.com/aj/note/Computer_Science/Compiler%20Design/Unit6A/Syntax%20Trees.php#.W2vi2dIzZPY