Suppose a flower had normal expression of genes A and C and expression of gene B in all four whorls. Based on the ABC hypothesis, what would be the structure of that flower, starting at the outermost whorl? a. carpel-petal-petal-carpel b. petal-petal-stamen-stamen c. sepal-carpel-carpel-sepal d. sepal-sepal-carpel-carpel