Respuesta :
Answer: A) part of the immune system does not function properly .
Immune system is a defense system which is present in the body of the organism that fights against the disease causing pathogens. Immune deficiency disorder is a state in which an immune system looses it's ability to fight against disease causing pathogen. This is responsible for making an organism prone to multiple diseases.
Therefore, someone with an immune deficiency disorder may get sick more easily than someone without the disorder because of the part of immune system does not function properly.