To solve this problem, we need to understand the consequences of adenosine deaminase deficiency.$\newline$Adenosine deaminase (ADA) is an enzyme that is crucial for the proper functioning of the immune system.$\newline$Let's analyze the options:$\newline \bullet$Option 1: Dysfunction of Immune system$\newline$ - ADA deficiency leads to the accumulation of toxic metabolites, which can harm lymphocytes.$\newline$ - This results in severe combined immunodeficiency (SCID), characterized by a dysfunctional immune system.$\newline$ - Therefore, this option is correct.$\newline \bullet$Option 2: Parkinson’s disease$\newline$ - Parkinson's disease is a neurodegenerative disorder unrelated to ADA deficiency.$\newline$ - Therefore, this option is incorrect.$\newline \bullet$Option 3: Digestive disorder$\newline$ - ADA deficiency primarily affects the immune system, not the digestive system.$\newline$ - Therefore, this option is incorrect.$\newline \bullet$Option 4: Addison’s disease$\newline$ - Addison's disease is an endocrine disorder affecting the adrenal glands, unrelated to ADA deficiency.$\newline$ - Therefore, this option is incorrect.$\newline$Based on the analysis, the correct answer is Option 1: Dysfunction of Immune system.