Which blood vessels have thick and elastic walls?

Options

A. Arteries
B. Veins
C. Capillaries
D. Lymph

Explanation

To answer the question "Which blood vessels have thick and elastic walls?", we can follow these steps:

### Step 1: Understand the Types of Blood Vessels
First, we need to recognize the main types of blood vessels in the circulatory system: arteries, veins, and capillaries. Each type has a specific function and structure.

### Step 2: Identify the Function of Arteries
Arteries are responsible for carrying blood away from the heart to various parts of the body. This blood is typically oxygenated and under high pressure.

### Step 3: Analyze the Structure of Arteries
Due to the high pressure of blood being pumped from the heart, arteries have thick and elastic walls. The elasticity allows them to stretch and accommodate the surge of blood with each heartbeat, while the thickness provides strength to withstand the pressure.

### Step 4: Compare with Other Blood Vessels
- **Veins**: Carry deoxygenated blood back to the heart. They have thinner walls and less elasticity compared to arteries because the blood pressure in veins is much lower.
- **Capillaries**: These are tiny blood vessels that connect arteries and veins. They have very thin walls to allow for the exchange of gases, nutrients, and waste products.
- **Lymph**: This is part of the lymphatic system, which helps transport lymph fluid, but it is not a blood vessel.

### Step 5: Conclude the Answer
Based on the analysis, the blood vessels that have thick and elastic walls are **arteries**. This structure is essential for their function of carrying high-pressure blood away from the heart.

### Final Answer
**Arteries have thick and elastic walls.**

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