Immunodeficiency occurs when the immune system is not working properly.
Many cancers can cause immunodeficiency.
Many cancers can cause the immune system to not work properly.
Many _ can cause the immune system to not work properly.

[a] fever
[b] bacteria
[c] radiation
[d] fungi
[e] A drug.
[f] Allergies
[g] cancers
[h] Toxicity