The human body has an organ A which acts as a pump. The pump A pumps a liquid B into the whole body continuously. The liquid B supplies the useful substances C and D to all the body cells and removes a waste E from the body cells.
What is the colour of liquid B?

Answer

**Step-by-Step Solution:**

1. **Identify the Organ (A)**: The question mentions an organ that acts as a pump in the human body. In humans, the heart is the organ that functions as a pump.

**Hint**: Think about which organ in the body is responsible for pumping blood.

2. **Identify the Liquid (B)**: The organ (heart) pumps a liquid throughout the body. This liquid is known as blood.

**Hint**: Consider what liquid circulates in the body and is essential for transporting substances.

3. **Identify Useful Substances (C and D)**: The blood supplies useful substances to the body cells. Common useful substances include nutrients (C) and oxygen (D).

**Hint**: Recall what the body needs to function properly and what is delivered to cells via the bloodstream.

4. **Identify the Waste (E)**: The blood also removes waste from the body cells. A common waste product that is removed is carbon dioxide (E).

**Hint**: Think about what byproducts are produced by cells that need to be expelled from the body.

5. **Determine the Color of Liquid (B)**: The question asks for the color of the liquid B, which we identified as blood. Blood is typically red in color due to the presence of red blood cells and hemoglobin.

**Hint**: Consider the visual appearance of blood and what gives it that color.

**Final Answer**: The color of liquid B (blood) is red.

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