Concept:The scolex is the specialised head region of a tapeworm that carries organs for attachment.
Explanation:In a tapeworm, the anterior end is modified into the scolex.
The labelled parts I, II and III are the different structures present on this head region.
These parts include suckers and, in some species, a rostellum armed with hooks.
All these structures work together as one attachment organ.
They help the parasite cling firmly to the intestinal wall of the host.
The proglottides are the body segments behind the head, not this head region.
A sucker is only a single component, while the rostellum is also only one part.
Therefore, the combined labelled parts form the whole head organ called the scolex.
Answer:D. scolex
