Correct Answer: C) Brain and spinal cord
Explanation
The nervous system is a part of the human body that helps us to communicate with the environment around us. It is responsible for sending and receiving messages between the brain and different parts of the body. The nervous system is made up of different parts, but the most important ones are the brain and spinal cord. These two organs are responsible for controlling and coordinating different body functions, including movement, sensation, and thought. Option A is incorrect because the kidney, bladder, and liver are not part of the nervous system. These organs are part of the urinary and digestive systems. Option B is also incorrect because the testes and ovaries are part of the reproductive system, not the nervous system. Option C is correct because the brain and spinal cord are the most important organs in the nervous system. The brain is responsible for receiving and interpreting information from the senses, processing thoughts and emotions, and controlling movement. The spinal cord is responsible for transmitting messages between the brain and different parts of the body. Option D is incorrect because muscles and skeleton are part of the musculoskeletal system, not the nervous system. In conclusion, the correct answer to the question is option C. The nervous system is made up of the brain and spinal cord, which are responsible for controlling and coordinating different body functions.