The correct option is B Calyx
Presence of pappus is a characteristic of family Asteraceae or Compositae. Pappus forms a parachute for wind dispersal of fruits.
In Asteraceae family, corolla is gamopetalous (i.e., corolla is composed of partially or fully fused petals). To make parachute, the object should be hairy and free from each other which will enable the floating.
Bract is a modified leaf which is generally associated with flower or inflorescence. Sepals like bracts are present in Asteraceae family which protect the flower before opening. Beyond that bract is not known to have any specific function.
Bracteoles are not known to have any specific function in Asteraceae family.
Calyx is reduced and modified into hairy pappus in Asteraceae family.
Therefore, the correct answer is option B.