Which of the following statements is true?
a. realistic painting has always been an important goal of art.
b. there is no way to know what the goal of a work of art is.
c. the goals of art are constantly changing.
d. artists are only influenced by their own thoughts and desires.

The correct answer is C. The goals of art are constantly changing. The concept of art is subjective, meaning that there's not one sole authority who says what art as a whole is trying to achieve. Instead, the goal of art will change depending on who's making and/or viewing it. Option A is incorrect because realistic painting is confined to a specific movement and time period, meaning that it wasn't always an important goal of art. Option B is incorrect, because an artist will often explain the goal of their work. Option D is incorrect, because artists are often influenced by previous movements, by muses, by education, etc.