The enzyme ADA, that is crucial for the immune system to function is abbreviated as :

Options

A. Adenosine deoxyaminase
B. Adenosine deaminase
C. Aspartate deaminase
D. Arginine deaminase

Answer

To solve the question regarding the abbreviation of the enzyme ADA that is crucial for the immune system, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Enzyme**: The question asks about the enzyme abbreviated as ADA, which is important for the immune system.

2. **Evaluate the Options**: We have several options to consider:
- Option 1: Adenosine deoxyaminase
- Option 2: Adenosine deaminase
- Option 3: Spartan daminase
- Option 4: Arginine daminase

3. **Analyze Each Option**:
- **Option 1**: Adenosine deoxyaminase - This is incorrect because the correct term for ADA is not deoxyaminase.
- **Option 2**: Adenosine deaminase - This is the correct abbreviation for ADA. This enzyme plays a crucial role in the immune system by converting toxic deoxyadenosine into a non-toxic form.
- **Option 3**: Spartan daminase - This option is incorrect as it does not relate to ADA.
- **Option 4**: Arginine daminase - This option is also incorrect as it does not correspond to the enzyme ADA.

4. **Conclusion**: The correct abbreviation for the enzyme ADA that is crucial for the immune system is **Adenosine deaminase**.

### Final Answer:
The enzyme ADA is abbreviated as **Adenosine deaminase**.

---