Certain Parasites,such as Intestinal Tapeworms,cannot Survive Outside of the Host

Multiple Choice

Certain parasites,such as intestinal tapeworms,cannot survive outside of the host.Why are they still considered alive?

A) Survival outside of a host is not a requirement for life.
B) They are still considered alive because they are studied by biologists, and biology is the study of life.
C) As long as they are made of cells, they are considered to be alive.
D) Because they cannot survive outside of the host, parasites are not considered alive.