Correct answer: C. Beautiful visual effect
Explanation: Direct answer: Option C, a beautiful visual effect. In art, form means the shape, structure or arrangement of things, while colour includes hue, lightness and intensity. When artists combine them thoughtfully, the viewer notices balance, contrast, emphasis, mood and beauty. The reasoning is: form gives an object its visible structure; colour adds visual character and feeling; together they create an organised visual effect in a drawing, painting or design. Option A is wrong because a planned combination does not create only disorder; it can create harmony and balance. Option B is wrong because sound belongs mainly to the auditory sense, while form and colour are visual elements. Option D is wrong because the combination adds visual meaning or attraction rather than producing only emptiness. The result may be realistic, abstract, calm or dramatic, but it is still a visual effect. Memory cue: form is shape, colour is visual feeling; together they make the picture speak.