Which of the Following Would Be Considered a Parasitic Relationship

Which of the following would be considered a parasitic relationship?

A) Some species of crabs decorate their shells with sea anemones and other corals. These "decorations" help camouflage the crab and the movement of the crab from one area to the next exposes the corals and anemones to different sources of food.
B) Some spiders do not build webs, but live in the web of another species. When a prey item is caught in the web, the non-web building spider will sneak in and steal the prey.
C) A praying mantis hunting and eating a fly.
D) The longest tapeworm removed from a human was approximately 11 meters long. Tapeworms do not have a digestive system, but obtains all of their nutrients from the host which can cause problems for the host especially if (s) he is undernourished.
E) Pseudoscorpions are small, harmless arachnids. To move from one place to another, they will sometimes latch onto the legs of flies and thus be carried long distances that they would not readily be able to traverse.