A carbohydrate that is formed by the body or by plants after the conversion of simple carbohydrates, supplying the body with long-term energy is called?

The correct answer is complex carbohydrates. These carbohydrates consist of long chains of sugar molecules that are more complex than simple carbohydrates. They are formed when the body or plants combine simple carbohydrates, leading to structures that take longer to break down during digestion. This prolonged breakdown process means that complex carbohydrates provide a more sustained source of energy over time, making them particularly valuable for maintaining energy levels throughout the day.

In contrast, simple carbohydrates are composed of shorter chains and typically provide a quick burst of energy but are often followed by a rapid decline in blood sugar. Water-soluble vitamins refer to essential nutrients that dissolve in water and function in various metabolic processes but do not serve as a source of energy. Lastly, the Reference Daily Intake (RDI) is a guideline for nutrient consumption levels and does not pertain directly to carbohydrate classification or their role in supplying energy. Thus, complex carbohydrates are indeed the correct choice when describing carbohydrates that provide long-term energy for the body.