The correct option is
C Olfactory receptor
The olfactory organ in certain molluscs is the osphradium.The organ is present in all members of the genus Conus. This is the group of the cone snails. This is the group of predatory sea snails. The main function of this organ is to test and analyze the incoming water for silt. the organ also helps in the detection of the possible food particles. They are the organs which are also linked with the respiration organ.Thus, the correct answer is option C.