The characteristic feature of anamnestic response is

Options

A. a highly intensified strong response which leads to a high titre of antibodies.
B. IgM is the dominant antibody in the body
C. a low intensity of antibodies which takes a longer time to establish immunity
D. Both (A) and (C )

Answer

### Step-by-Step Solution:

1. **Understanding Anamnestic Response**:
- The anamnestic response refers to the immune system's ability to recognize and respond more vigorously to an antigen that it has encountered previously. This is a form of immunological memory.

**Hint**: Recall that anamnestic response is linked to the concept of memory in the immune system.

2. **Role of Antibodies**:
- When the immune system first encounters an antigen, it produces antibodies specific to that antigen. If the same antigen re-enters the body, the immune system can quickly produce these antibodies again.

**Hint**: Think about how the body "remembers" pathogens it has fought off before.

3. **Characteristics of the Response**:
- The anamnestic response is characterized by a rapid and robust production of antibodies, particularly IgG, which is more effective than the initial response that primarily involves IgM.

**Hint**: Consider the difference between primary and secondary immune responses in terms of antibody types and response time.

4. **Identifying the Correct Option**:
- The question asks for the characteristic feature of the anamnestic response. The correct option states that it is a "highly intensified, strong response which leads to a high titer of antibodies." This is accurate because the second exposure to the antigen results in a much stronger and faster immune response.

**Hint**: Focus on the intensity and speed of the immune response when the same antigen is encountered again.

5. **Eliminating Incorrect Options**:
- The other options mention low intensity of antibodies and a longer time to establish immunity, which do not describe the anamnestic response accurately. The dominant antibody in the secondary response is IgG, not IgM.

**Hint**: Compare the features of the anamnestic response with the characteristics of primary immune responses.

### Final Answer:
The characteristic feature of anamnestic response is a highly intensified, strong response which leads to a high titer of antibodies.