The antibodies that can bind the largest number of antigens is ………while the antibody that is smallest in size is ………
Choose the option that correctly fills the blanks

Options

A. IgA, IgM
B. IgM, IgA
C. IgG, IgD
D. IgM, IgG

Answer

To solve the question, we need to identify two specific types of antibodies based on the criteria given: the antibody that can bind the largest number of antigens and the antibody that is smallest in size.

### Step-by-Step Solution:

1. **Understanding Antibodies**: Antibodies, also known as immunoglobulins, are proteins produced by the immune system to identify and neutralize foreign objects like bacteria and viruses.

2. **Identifying the Antibody that Binds the Largest Number of Antigens**:
- Among the different classes of antibodies (IgA, IgM, IgG, IgD, and IgE), IgM is known for its ability to bind multiple antigens.
- IgM is a pentamer, meaning it consists of five antibody units joined together, which allows it to bind to multiple antigens simultaneously. This makes it particularly effective in the initial immune response.

3. **Identifying the Smallest Antibody**:
- When considering the size of antibodies, IgG is the smallest among the main classes of immunoglobulins.
- IgG is a monomer, meaning it consists of a single unit, which contributes to its smaller size compared to other antibodies like IgM.

4. **Final Answer**:
- Therefore, the antibody that can bind the largest number of antigens is **IgM**, and the smallest antibody in size is **IgG**.

### Conclusion:
The correct option that fills the blanks is **IgM and IgG**.