Three Weeks After a River Rafting Trip, Three Family Members

Three weeks after a river rafting trip, three family members experienced symptoms of coughing, fever, and chest pain. During the rafting trip, the family had consumed crayfish that they caught along the river banks. An examination of the patientsʹ sputum revealed helminth eggs, and serum samples were positive for antibodies to Paragonimus. All of the family members recovered following treatment with praziquantel. In the Paragonimus life cycle,

A) both humans and crayfish are definitive hosts.
B) humans are the definitive host and crayfish are the intermediate host.
C) the source of the infection was the river water.
D) both humans and crayfish are intermediate hosts.
E) the crayfish are the definitive host and humans are the intermediate host.