21. In a particular species of plants, when the soil pH is greater than 7, blue flowers are produced. However, when the soil pH is less than 7, pink flowers are produced. Which statement best explains the color change in the plant? A) Multiple alleles determine the color of the flowers.
B) The change in flower color is a result of a mutation.
C) Polygenic inheritance produces the different flower colors.
D) The environment influences the expression of the gene for flower color.