Concept:The parachute-like tuft of hairs in seeds like Tridax is a modification of the calyx, which consists of sepals.
Explanation:The tuft of hairs, known as a pappus, helps in wind dispersal of fruits.
In plants such as Tridax, these hairs are formed from the persistent calyx.
The calyx is made up of sepals, which become modified into hair-like structures.
Thus, the pappus develops from sepals, not from the pedicel, petals, or receptacle.
Answer:D. sepals