I) Primary lymphoid organs include .....A.....and .....B..... In these organs immature lymphocytes differentiate into antigen sensitive lymphocytes. After maturation, the lymphocytes migrate to ......C....
II) .....D..... is the site for the development and maturation of B-lymphocytes
III) Thymus is the site for the development and maturation of .....E.....
Here A to E refers to

Options

A. A-liver, B-bone marrow, C-main lymphoid organ, D-Thymus, E-T-lymphocyte
B. A-bone marrow, B-thymus, C-tertiory lymphoid organs, D-Thymus, E-B-lymphocyte
C. A-bone marrow, B-thymus, C-secondary lymphoid organs, D-Bone marrow, E-T lymphocyte
D. A-heart, B-liver, C-main lymphoid organ, D Thymus, E-B-Lymphocyte

Answer

To solve the question, we need to fill in the blanks A to E based on our understanding of primary and secondary lymphoid organs as well as the development of lymphocytes.

### Step-by-Step Solution:

1. **Identify Primary Lymphoid Organs**:
- The primary lymphoid organs are responsible for the maturation of lymphocytes. The two primary lymphoid organs in humans are the **bone marrow** and the **thymus**.
- Therefore, for blanks A and B:
- A = **Bone marrow**
- B = **Thymus**

2. **Maturation and Migration of Lymphocytes**:
- After lymphocytes mature in the primary lymphoid organs, they migrate to the **secondary lymphoid organs**. These include lymph nodes, spleen, and tonsils.
- Thus, for blank C:
- C = **Secondary lymphoid organs**

3. **Development and Maturation of B-Lymphocytes**:
- The site for the development and maturation of B-lymphocytes is the **bone marrow**.
- Therefore, for blank D:
- D = **Bone marrow**

4. **Development and Maturation of T-Lymphocytes**:
- The thymus is specifically the site for the development and maturation of **T-lymphocytes**.
- Hence, for blank E:
- E = **T-lymphocytes**

### Final Answers:
- A = Bone marrow
- B = Thymus
- C = Secondary lymphoid organs
- D = Bone marrow
- E = T-lymphocytes

### Summary of the Filled Blanks:
I) Primary lymphoid organs include **Bone marrow** (A) and **Thymus** (B). In these organs, immature lymphocytes differentiate into antigen-sensitive lymphocytes. After maturation, the lymphocytes migrate to **Secondary lymphoid organs** (C).
II) **Bone marrow** (D) is the site for the development and maturation of B-lymphocytes.
III) Thymus is the site for the development and maturation of **T-lymphocytes** (E).