​ How Does the Artist Guan Daosheng Achieve the Effect of Effect

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How does the artist Guan Daosheng achieve the effect of mist in her painting Bamboo Groves in Mist and Rain ?

A) By showing groups of bamboo in the background
B) By restricting the ink tones to a narrow range
C) By using many thick, even black lines
D) By adding a wash of grey watercolor over the ink