A way for sepals and petals to look like one another (collectively “tepals”) would be for the expression of B class genes to spread to the outermost (sepal) whorl, giving them A and B class gene expression. That would cause petal-specific genes to be expressed in sepals, changing their appearance to that of petals.
Work Step by Step
This question is asking you to review pp. 774-775, especially Fig. 35.35. You can see there that the expression of different gene classes determines the appearance and function of flower parts, so use your imagination and that information to determine which classes of genes would have to be expressed in the outer whorl to get the sepals to look like petals.