A disease in which the immune system attacks "self' tissue is known as a(n) immunodeficiency.
primary immunodeficiency.
autoimmune disease.
secondary immunodeficiency​

Autoimmune disease

Explanation:

this occurs when the body's immune system attacks and destroys healthy body tissue by mistake. there are more than 80 types of Autoimmune disorders.

some examples include:lupus( an inflammatory disease caused when the immune system attacks its organs like your kidneys and heart)

another example is celiac disease ( when you have an immune reaction to gluten a protein found in wheat, barley, and rye. you can have bloating and low blood count).

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multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).   so the answer is a.