Select the correct option to fill up the blanks.
(i) Diseases which are easily transmitted from one person to another, are called ______ diseases.
(ii) In human body, parasite of malaria initially multiplies within the ____ and then attack the ______.
(iii) _____ is the yellowish fluid secreted by mother during the initial days of lactation.
(iv) _____ and ____ are the primary lymphoid organs.

Options

A. (i) infectious, (ii) bone marrow, thymus, (iii) Colostrum, (iv) Liver cell, RBCs
B. (i) infectious, (ii) liver cell, RBCs, (iii) Colostrum, (iv) Bone marrow, thymus
C. (i) interferon, (ii) bone marrow, thymus, (iii) Colostrum, (iv) Liver cell, RBCs
D. (i) infectious, (ii) liver cell, RBCs, (iii) Colostrum, (iv) Spleen, lymph node

Answer

To solve the question, we need to fill in the blanks with the correct terms based on our understanding of human health and diseases. Let's go through each blank step by step.

### Step-by-Step Solution:

1. **First Blank**:
- The question states, "Diseases which are easily transmitted from one person to another, are called ______ diseases."
- The correct term for diseases that can be transmitted from one person to another is **"infectious"** or **"communicable"** diseases.
- **Answer**: Infectious

2. **Second Blank**:
- The question states, "In human body, parasite of malaria initially multiplies within the ____ and then attack the ______."
- The malaria parasite, known as Plasmodium, initially multiplies in the **"liver"** and then attacks the **"RBCs" (red blood cells)**.
- **Answer**: Liver, RBCs

3. **Third Blank**:
- The question states, "_____ is the yellowish fluid secreted by mother during the initial days of lactation."
- The yellowish fluid secreted by the mother during the initial days of lactation is called **"colostrum."**
- **Answer**: Colostrum

4. **Fourth Blank**:
- The question states, "_____ and ____ are the primary lymphoid organs."
- The primary lymphoid organs where the maturation of immune cells occurs are the **"bone marrow"** and **"thymus."**
- **Answer**: Bone marrow, Thymus

### Final Answers:
1. Infectious
2. Liver, RBCs
3. Colostrum
4. Bone marrow, Thymus

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