Instant source of energy is Glucose.

Glucose is the correct answer for an instant source of energy. Here is a detailed explanation:

What is energy?
Energy is the ability to do work or the capacity for action. It is what allows our bodies to function and perform various activities.

How do we get energy?
We get energy by consuming food and breaking it down through a process called digestion. The nutrients present in our food are converted into energy that our body can use.

What is glucose?
Glucose is a type of sugar and the primary source of energy for our body's cells. It is a simple carbohydrate that is easily broken down and absorbed by the body.

Why is glucose an instant source of energy?
Glucose is considered an instant source of energy because it is quickly and easily converted into cellular energy. Once we consume glucose-rich foods, our body rapidly absorbs it into the bloodstream. From there, it is transported to the cells where it can be used immediately for energy production.

Other options:
Let's briefly discuss the other options mentioned in the question and why they are not considered instant sources of energy:

a) Sugar: Sugar is a type of carbohydrate that contains glucose. However, not all sugars are instantly available for energy. Complex sugars, such as sucrose found in table sugar, need to be broken down into glucose before they can be used as an energy source.

b) Fat: While fat is an important source of energy, it is not an instant source. Fat molecules are larger and more complex than glucose molecules, requiring more time and effort to break down and convert into usable energy.

c) Vitamins: Vitamins are essential nutrients that play various roles in our body's functions. However, they are not a direct source of energy. Vitamins help support energy production by assisting in the metabolism of carbohydrates, fats, and proteins.

In conclusion, glucose is the correct answer for an instant source of energy. It is quickly absorbed and utilized by our body's cells, providing the immediate energy needed for various activities.