The correct options are
B Parasite feeds and multiplies in the definitive host and remains dormant in the reservoir host
C Parasite causes symptoms in the definitive host but does not damage the reservoir host
D Both the definitive and reservoir host are required for completion of the life cycle of the parasite
The definitive host is the one in which a parasitic organism multiplies and causes infection leading to symptoms of the disease. The reservoir host harbours the pathogen in a dormant state. It is a carrier for the pathogen.