Explanation:

In our body, there are three types of muscles:

1. Voluntary or Skeletal Muscles: These muscles are under our conscious control. They are responsible for the movement of our body parts like arms, legs, etc. These muscles are attached to bones by tendons.

2. Involuntary or Smooth Muscles: These muscles are not under our conscious control. They are present in the walls of hollow organs like the stomach, intestines, blood vessels, etc. These muscles help in the movement of substances through these organs.

3. Cardiac Muscles: These muscles are present in the heart and are responsible for the pumping of blood. They are under the control of the autonomic nervous system.

The answer to the given question is option 'B' because involuntary or smooth muscles are not under our conscious control. These muscles are responsible for the movement of substances through hollow organs like the stomach, intestines, blood vessels, etc. They work automatically without us having to think about it.

Examples of Involuntary or Smooth Muscles:

- Muscles in the walls of the digestive system help in the movement of food through the digestive tract.
- Muscles in the walls of blood vessels help in the regulation of blood pressure and the flow of blood.
- Muscles in the walls of the respiratory system help in the movement of air in and out of the lungs.

Conclusion:

Involuntary or smooth muscles are not under our conscious control. They work automatically to help in the movement of substances through hollow organs in our body.