The correct option is A bracts
The green leaf-like structures that protect the flower bud are called bracts. In some flowers, bracts surround the sepals and in some it does not.
Calyx is the outermost whorl of the flower and the members are called sepals.
Corolla is the next whorl to calyx and is composed of petals. It is meant to attract pollinators with its bright colours.
The broadened base of a flower which lies at the tip of the pedicel is called thalamus or receptacle.