The energy to sustain normal daily activities is provided by

Carbohydrates.

Explanation:

Carbohydrates are very essential food nutrients that meet out our entire cellular energy requirement. They play a special role of providing energy during exercise and are commonly found is grains (wheat, rice), fruits, vegetable, milk products and beans. They make human being sharper and provide energy for all their metabolic process with in the body.

Carbohydrates are broken down into simple sugar molecules such as glucose, fructose, and galactose.