The correct answer is option C: Autonomic nervous system.

The autonomic nervous system (ANS) is responsible for the regulation and control of the internal organs of the body. It is a part of the peripheral nervous system (PNS), which is the division of the nervous system that is outside of the brain and spinal cord.

The ANS controls involuntary actions of our internal organs, such as the beating of the heart, digestion, breathing, and the release of hormones. It operates independently of conscious control and helps to maintain homeostasis in the body.

Let's understand the activities of the internal organs and how they are controlled in more detail:

**Central Nervous System (CNS)**
The central nervous system consists of the brain and spinal cord. It receives and processes information from the body and sends out appropriate signals to control body functions. While the CNS plays a vital role in coordinating and regulating the activities of the body, it does not directly control the internal organs.

**Peripheral Nervous System (PNS)**
The peripheral nervous system consists of nerves that connect the central nervous system to the rest of the body. It is further divided into two major components: the somatic nervous system and the autonomic nervous system.

**Somatic Nervous System**
The somatic nervous system controls voluntary actions and is responsible for the conscious movement of our skeletal muscles. It allows us to interact with the external environment by carrying sensory information to the CNS and transmitting motor commands from the CNS to the skeletal muscles.

**Autonomic Nervous System**
The autonomic nervous system, as mentioned earlier, controls the involuntary activities of the internal organs. It can be further divided into two branches: the sympathetic nervous system and the parasympathetic nervous system.

The sympathetic nervous system prepares the body for action and is responsible for the "fight or flight" response. It increases heart rate, dilates blood vessels, and mobilizes energy to help the body respond to stress or danger.

On the other hand, the parasympathetic nervous system promotes relaxation and helps the body conserve energy. It slows down heart rate, constricts blood vessels, and promotes digestion and elimination.

The activities of the internal organs are regulated by a balance between the sympathetic and parasympathetic branches of the autonomic nervous system. These two branches work together to maintain homeostasis by adjusting organ function according to the body's needs.

In conclusion, the activities of the internal organs are controlled by the autonomic nervous system, which is a part of the peripheral nervous system. The autonomic nervous system consists of the sympathetic and parasympathetic branches, which work together to regulate the internal organ functions and maintain homeostasis in the body.

A