Hint: The pharynx is a hollow tube like structure which lies behind the nose and runs down to the neck and ends in the opening of the food pipe and windpipe. It is a part of the digestive tract which carries food from the mouth.
To answer this question, we must know in which organism everted pharynx it is present.
A) Dugesia- It is a platyhelminth. The digestive tract of Dugesia contains central non pigmented tubular pharynx called the everted pharynx. It is located in the pharyngeal cavity which is held by a muscular pouch called the pharyngeal sheath. The pharynx is everted through the mouth as proboscis which helps in feeding.
B) Fasciola- It is commonly known as liver fluke. It consists of a mouth which opens at the esophagus through the pharynx.
C) Taenia- It is a genus of tapeworm. They have a segmented body. They do not have pharynx and have short necks.
D) Ascaris- It is commonly known as roundworm. It has a short segmented body and lack larynx.
Thus, the correct answer is option ‘A’. Dugesia.
Note: The regeneration is common in Dugesia and it belongs to the class turbellaria. It is nocturnal and reproduction is sexual as well as asexual. It is also called flatworm found in freshwater of Africa, Europe. They are parasitic organisms which live on more than one host. They have auricles behind the eyes which help in detecting the intensity of water current.