Read the passage and answer the following question.

The human body is a wonderful machine. It performs several functions without rest from birth. Our body continues to work, without stopping for a second. The main organs of the human body are the lungs, heart, kidney, liver, and brain. These organs work together and are controlled by the brain. Each system carries out a major function, digestive system, excretory system, circulatory system, endocrine system, nervous system, muscular system, etc. All are controlled by the brain. The brain gives us the intelligence to use our physical and mental abilities. The body has more than 50,000 living cells of two hundred different types. These cells include neurons (nerve cells) and glands (specialized cells). The hormones and enzymes are produced and secreted by these glands. Various types of cells perform different functions. Cells doing the similar jobs are grouped to form tissues. The tissues group together in a special manner to form organs.

The human body is covered by the skin. Skin is a flexible covering that protects the body. It keeps water and harmful germs out. It is war resistant. The body’s strong internal framework (skeleton) is made of 206 bones. These are connected at the joint, such as in the legs. These joints help us to move. The backbone supports the head and limbs and protects the spinal cord. Between the skeleton and skin, there are about 500 muscles. Nerves spread from the brain to all parts of the body. They carry signals in the form of tiny electrical impulses, the sense organs, namely the eyes, nose, ears, tongue, and skin, pass the messages to the brain through nerves. They take the instructions from the brain to the muscles. The brain automatically controls breathing, heartbeat, digestion, etc. The body keeps on growing. The peak of physical growth is reached at about 18 to 25 years of age. When we grow old the skin becomes wrinkled and less elastic. The joints become inflexible, muscles loose, and bones become weak. At the climax of life, the body gives up and death occurs.

The human body is the most valuable gift of God to human being. A healthy body contains a healthy brain. A healthy brain contains a healthy soul. As such, it is very important to take care of our bodies. For this regular exercise, control over eating habits, cleanliness of body, and discipline are essential in daily life.

Which of the following system is not present in the body? 

None of the above 

All three systems are present in the body which enable the body to function properly.