Which structure on a tapeworm aids in attachment to the host?

The scolex is the structure on a tapeworm that is specifically adapted for attachment to the host's intestinal wall. This specialized region features hooks and suckers that allow the tapeworm to firmly anchor itself and resist being expelled by the host's digestive processes.

In the context of a tapeworm's lifecycle, the ability to securely attach to the host is critical for its survival and reproduction. By clinging to the intestinal lining, the scolex enables the tapeworm to absorb nutrients from the host's digestive contents, which is essential for its growth and development.

The other structures mentioned, such as proglottids, are segments of the tapeworm that contain reproductive organs and help in disseminating eggs, but they do not play a direct role in attachment. The tegument is the outer covering of the tapeworm that protects it from the host’s immune system and digestive enzymes but is not involved in attachment. The radula, on the other hand, is a feeding structure found in mollusks and does not apply to tapeworms at all.