The correct option is D achlamydeous
The non-essential whorls of a flower are calyx and the corolla since they are not responsible for the formation of gametes and seeds. When both non-essential whorls (calyx and corolla) are absent then the flower is described as achlamydeous.
When both the non-essential whorls are present then the flower is described as dichlamydeous.
If only one non-essential whorl is present then the flower is described as monochlamydeous.
When a single plant has separate male and female flowers, then this condition is called monoecy.
When male and female flowers are present in different plants in a species, Then, the condition is called dioecy.