The correct option is
A Imbricate
Aestivation refers to the arrangement of the petals or sepals in a flower.
A. When the margins of the sepals or petals overlap one another without any particular direction, it is called imbricate. Example Cassis.
B. When the margins of the sepals or petals overlap one another regularly in the particular direction, it is called twisted, example, China Rose.
C. When the margins of the sepals or petals do not overlap one another, it is called valvate, example Calotropis.
D. When the petals are of different sizes and show descending imbricate pattern, it is called vexillary, example, pea.
So, the correct answer is 'Imbricate'