Concept:Tapeworm is an internal parasite so the control method must deliver treatment inside the sheep's body.
Explanation:Methods like dusting, spraying, and dipping are mainly applied to the skin or coat of the sheep.
Therefore, they are suitable for external parasites such as ticks, lice, and mites.
In contrast, tapeworm lives inside the digestive system of sheep.
It attaches to the intestinal wall where external treatments cannot reach it.
Drenching is the oral administration of liquid anthelmintic medicine.
The medicine is poured into the animal's mouth and swallowed.
It passes into the stomach and intestines where it acts against tapeworm.
Hence, drenching is the correct method for controlling tapeworm in sheep production.
Answer:D. drenching