Answer:
B. They are parasitic.
D. They cause diseases in humans.
Explanation:
Worms are known and classified in Biology as Helminths. They are invertebrates which means they do not have backbones.
Helminths(worms) vary in their body shapes. Some are long, Some have a round shape while some are flat.
Some helminths have a digestive tracts while some do not. Some are hemaphrodites while some are bisexual.
Helminths are parasitic organisms and when found in body of animals, they tend to attach themselves to internal organs such as the digestive tracts of humans. They can cause illness in the body.
Types of Helminths include: Round worms, Tape worms, flukes, flatworms e.t.c.