The _________1_____________ is the main lymphoid organ where all blood cells _________2_____________ lymphocytes are produced. The _________3_____________ is a lobed organ located near the heart and beneath the breastbone. The _________3_____________ is quite large at the time of birth but keeps reducing in size with age and by the time puberty is attained it reduces to a very small size. Both _________1_____________ and _________3_____________ provide micro-environments for the development and maturation of T-lymphocytes.

Options

A. `{:("(1)","(2)","(3)"),("bonemarrow","including","thymus"):}`
B. `{:("(1)","(2)","(3)"),("spleen","including","thymus"):}`
C. `{:("(1)","(2)","(3)"),("thymus","excluding","bonemarrow"):}`
D. `{:("(1)","(2)","(3)"),("bonemarrow","excluding","spleen"):}`

Answer

To solve the question, we need to fill in the blanks with the correct terms related to lymphoid organs and the production of lymphocytes. Let's break it down step by step.

### Step-by-Step Solution:

1. **Identify the Main Lymphoid Organ**:
- The question states, "The _________1_____________ is the main lymphoid organ where all blood cells _________2_____________ lymphocytes are produced."
- The main lymphoid organ responsible for producing all blood cells, including lymphocytes, is the **bone marrow**.
- **Fill in the blank 1**: Bone marrow

2. **Identify the Term for Blood Cells**:
- The phrase "where all blood cells _________2_____________ lymphocytes are produced" suggests that we need a word that indicates the inclusion of lymphocytes in the blood cells produced.
- The appropriate term to fill in this blank is **including**.
- **Fill in the blank 2**: Including

3. **Identify the Lobed Organ**:
- The next part of the question states, "The _________3_____________ is a lobed organ located near the heart and beneath the breastbone."
- The organ that fits this description is the **thymus**.
- **Fill in the blank 3**: Thymus

4. **Summarize the Information**:
- The thymus is indeed a lobed organ that is larger at birth and decreases in size with age, particularly by puberty. Both the bone marrow and thymus provide environments for the development and maturation of T-lymphocytes.

### Final Answers:
- **Blank 1**: Bone marrow
- **Blank 2**: Including
- **Blank 3**: Thymus

### Complete Statement:
The **bone marrow** is the main lymphoid organ where all blood cells **including** lymphocytes are produced. The **thymus** is a lobed organ located near the heart and beneath the breastbone. The **thymus** is quite large at the time of birth but keeps reducing in size with age and by the time puberty is attained it reduces to a very small size. Both **bone marrow** and **thymus** provide micro-environments for the development and maturation of T-lymphocytes.