The correct answer is B, Anisakis simplex.  Adult Anisakis simplex infect mammals such as whales and seals.  Fish serve as the intermediate host.  The worms inhabit the stomachs of the definitive hosts and produce eggs, which are passed in feces into the seawater.  Each egg develops a larva that hatches to become part of the zooplankton.  Larvae are ingested by squid and other macroinvertebrates, and develop into an infective stage.  Ingestion of these infected animals by fish moves the larvae up the food chain.  When the final host ingests infected fish or macroinvertebrates, the worms can complete their life cycles.  In humans, the worms do not mature to the adult stage, but the immature worms do attach to the stomach wall and result in acute symptoms consisting primarily of intense gastric pain.

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