Educational diagram illustrating the circulatory system, including the heart, arteries, veins, and lungs, with descriptions of their functions.

Let's solve the labeling task step by step based on the provided image and descriptions.

We are given four terms to label: lungs, heart, veins, and arteries. We need to match each term with the correct description and place it in the corresponding box.

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Step 1: Analyze Each Description

#### Description 1 (Top right):
> "They return blood to the heart. This blood is darker (usually look blue) because they have low oxygen."

- Blood returning to the heart has low oxygen.
- These are veins.
✔ Label: veins

#### Description 2 (Bottom left):
> "They carry bright red blood full of oxygen from the heart to all the parts of the body."

- Bright red blood = oxygen-rich
- Carrying blood from the heart to the body
- These are arteries
✔ Label: arteries

#### Description 3 (Middle left):
> "It is a hard working muscle that pumps blood to every parts of the body."

- This refers to the heart, which is a muscular organ that pumps blood.
✔ Label: heart

#### Description 4 (Bottom right):
> "They take the oxygen we need to live."

- This describes where oxygen is taken in — the lungs.
- The lungs are responsible for gas exchange: taking in oxygen and releasing carbon dioxide.
✔ Label: lungs

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Final Answer:

Now, fill in the boxes accordingly:

1. Top right box:
→ "They return blood to the heart..."
✔ veins

2. Middle left box:
→ "It is a hard working muscle that pumps blood..."
✔ heart

3. Bottom right box:
→ "They take the oxygen we need to live."
✔ lungs

4. Bottom left box:
→ "They carry bright red blood full of oxygen..."
✔ arteries

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Summary of Labels:

| Box Location | Label |
|---------------------|-----------|
| Top right | veins |
| Middle left | heart |
| Bottom right | lungs |
| Bottom left | arteries |

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Explanation:

- Arteries carry oxygenated (bright red) blood away from the heart to the body.
- Veins carry deoxygenated (darker/blue) blood back to the heart.
- The heart is the central pump of the circulatory system.
- The lungs are where oxygen enters the bloodstream and carbon dioxide is removed.

This completes the labeling task correctly!