Answer:
3. organization of the painting's various images on the canvas
Step-by-step explanation:
The composition is the disposition of the elements on the canvas. That's the essence of the art piece usually, that's where the artist express his/her ideas and choses the way to present it to the world.
Color choice is also important, but not as much, unless it's a totally abstract painting.
It's the same thing in photography and in many other art forms.