Answer:

Introduction:
The human body is a complex organism made up of various components that work together to ensure its proper functioning. One of the critical components of the human body is water, which makes up a significant percentage of our overall body composition.

Body:

Water and its Importance:
Water is an essential substance that is vital for the survival of all living organisms. It plays a crucial role in maintaining various bodily functions, such as regulating body temperature, aiding digestion, transporting nutrients, lubricating joints, removing waste products, and supporting overall cellular functions.

Percentage of Water in the Human Body:
About 70% of our body consists of water. This percentage may vary depending on various factors such as age, gender, body composition, and overall health. However, it is generally agreed upon that water makes up a significant proportion of our body weight.

Functions of Water in the Human Body:
1. Hydration: Water is essential for maintaining proper hydration levels in our body. It helps to replenish the body's water supply lost through activities such as sweating, urination, and breathing.

2. Temperature Regulation: Water acts as a coolant and helps regulate body temperature. It absorbs heat generated during various metabolic processes and releases it through sweat, which evaporates from the skin surface.

3. Digestion and Nutrient Absorption: Water is necessary for proper digestion and absorption of nutrients. It helps break down food particles, facilitates the movement of digested food through the digestive tract, and aids in the absorption of nutrients into the bloodstream.

4. Waste Removal: Water plays a crucial role in eliminating waste products from the body. It helps flush out toxins and waste materials through urine, sweat, and bowel movements.

5. Lubrication: Water acts as a lubricant for joints, allowing smooth movement and reducing friction between bones and cartilage.

6. Cellular Functions: Water is involved in various cellular processes, including nutrient transport, waste removal, and chemical reactions necessary for proper cell functioning.

Conclusion:
Water is a vital component of the human body, constituting about 70% of our overall body weight. It plays numerous critical roles in maintaining overall health and ensuring the proper functioning of various bodily systems. Therefore, it is essential to stay adequately hydrated by consuming an adequate amount of water daily.

A is correct .