Final answer:
The statement 'Inaccessible to its host’s immune system' describes an endoparasite, which lives inside the host and is able to evade the immune system more effectively than an ectoparasite, which lives on the surface.
Step-by-step explanation:
The statement describing a parasite that is 'inaccessible to its host’s immune system' pertains to an endoparasite. Endoparasites, unlike ectoparasites, live inside their hosts, such as the intestines, blood, or tissues, which makes them less exposed to the host's immune responses. Ectoparasites, on the other hand, live on the surface of the host's body, making them more likely to encounter host defense mechanisms, such as the immune system or behavioral defenses like grooming. Endoparasites have sophisticated methods to evade the immune system, including the expression of surface molecules similar to the host's, which allows them to remain undetected. Examples of endoparasites include helminths such as hookworms and roundworms, which can disguise themselves from the immune response. In contrast, ectoparasites, such as fleas, ticks, and mites, are more likely to be targeted by the host's immune system since they live externally.