Which of the following is/are controlled by the human brain ?
a. Balance of the body
b. Circadian rhythm of the body
c. Human behaviour
d. Functioning of heart and kidneys

Options

A. Only d
B. a and d
C. a, b and c
D. a, b , c, d

Answer

To determine which functions are controlled by the human brain, let's analyze each option provided in the question:

1. **Balance of the body (Option a)**:
- The brain plays a crucial role in maintaining balance. The hindbrain, particularly the cerebellum, is involved in coordinating balance and motor control. Additionally, the vestibular apparatus in the inner ear sends sensory information about balance to the brain, which processes this information to maintain equilibrium.

2. **Circadian rhythm of the body (Option b)**:
- The brain regulates circadian rhythms, which are the physical, mental, and behavioral changes that follow a daily cycle. The suprachiasmatic nucleus (SCN) in the hypothalamus is responsible for controlling these rhythms by responding to light signals, thus influencing sleep-wake cycles and other bodily functions.

3. **Human behavior (Option c)**:
- Human behavior is significantly influenced by the brain, particularly through the limbic system, which is involved in emotions, memory, and motivation. The brain integrates various stimuli and responses, shaping our behavior and reactions.

4. **Functioning of heart and kidneys (Option d)**:
- While the autonomic nervous system, which is regulated by the brain, controls the functioning of the heart and kidneys, the brain does not directly control these organs. However, it does play a role in regulating their functions through hormonal and neural pathways.

Based on this analysis, we can conclude that all the options listed (a, b, c, and d) are functions that are influenced or controlled by the human brain. Therefore, the answer to the question is:

**All of the above (a, b, c, d)**.

### Summary of Steps:
1. Analyze the role of the brain in maintaining balance.
2. Examine how the brain regulates circadian rhythms.
3. Consider the brain's influence on human behavior.
4. Assess the brain's role in the functioning of heart and kidneys.
5. Conclude that all options are controlled by the brain.