It is independent because it expresses a complete tought.
Speech balloons, also known as speech bubbles, dialogue balloons or word balloons, are a graphic convention used most commonly in comic books, comics and cartoons to allow words to be understood as representing the speech or thoughts of a given character in the story or events of the graphic novel or Comic.
According to the information presented before I would conclude that the main purpose of a speech bubble in a graphic novel is:
D) It illustrates internal thoughts.
<span>I believe C. rising action</span>
<span>Over the course of two years, Gulliver describes the state of affairs in Europe, speaking to his Houyhnhnm master about the English Revolution and the war with France. He is asked to explain the causes of war, and he does his best to provide reasons. He is also asked to speak of law and the justice system, which he does in some detail, criticizing lawyers severely in the process.</span>
