Which one is correct about voluntary and involuntary movements?
A. Voluntary movements - caused by skeletal muscle, involuntary movements - caused by smooth muscle.
B. Voluntary movements - caused by smooth muscle, involuntary movements - caused by skeletal muscle.
C. Voluntary movements - controlled by the brain, involuntary movements - controlled by organs.
D. Voluntary movements - controlled by organs, involuntary movements- controlled by the brain.

Hint: Each and every movement in the human body is controlled and triggered in the brain. Both voluntary and involuntary movements are controlled by specific parts of the brain. The cerebellum is part of the human brain that controls locomotion and movement. The movement of the human body parts that the brain controls involve muscles, bones, tissues, etc.

Complete solution:
Voluntary movements are caused by skeletal muscles, whereas, involuntary movements are caused by smooth muscles. Smooth muscle movement is caused due to contraction, which is responsible for involuntary movements of the internal organs. These muscles move food through the digestive tract. In arteries, the diameter of the artery is also maintained by smooth muscle movements. On the other hand, skeletal muscles are responsible for voluntary movements. These muscles are attached to bones. When a signal for movement is initiated, the skeletal muscle moves the skeleton (bones). Some examples of voluntary muscles include the biceps, the triceps, the quadriceps, diaphragm, pectoral muscles, abdominals, hamstrings, etc. Whereas, examples of involuntary muscles include heart muscle, respiratory tracts, etc. Voluntary movements can be physically controlled, while involuntary movements can not be consciously controlled.
Hence, the correct answer is option A.

Note: Smooth muscles are also found in the internal lining of the digestive system, urinary tract, reproductive systems as well as in the airways and arteries. In the human eye, the pupillary sphincter muscles are smooth muscles responsible for shrinking the size of the pupil.