Choose the correct option for each question. There is only one correct response for each question.
Identify the cause of friction between two objects

Options

A. Gravitational force
B. Size of the objects
C. Mass of the objects
D. Irregularities on the surfaces of the objects

Answer

To solve the question "Identify the cause of friction between two objects," we need to analyze the provided options and determine which one correctly identifies the cause of friction.

### Step-by-Step Solution:

1. **Understanding Friction**:
- Friction is a force that opposes the motion of two surfaces in contact. It arises due to the interactions between the surfaces.

2. **Evaluating the Options**:
- **Option 1: Gravitational Force**: This is the force that attracts two bodies towards each other but does not directly cause friction.
- **Option 2: Size of the Objects**: While size may influence the contact area, it is not the primary cause of friction.
- **Option 3: Mass of the Objects**: Mass affects the normal force, which influences friction, but it is not the direct cause of friction itself.
- **Option 4: Irregularities on the Surface of Objects**: This option refers to the roughness or smoothness of the surfaces in contact. The irregularities create resistance to motion, which is the essence of friction.

3. **Conclusion**:
- The correct option is **Option 4: Irregularities on the surface of objects**. These irregularities are the primary cause of friction between two objects.

### Final Answer:
The cause of friction between two objects is **irregularities on the surface of objects** (Option 4).

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