The major source of energy for cells comes from d) carbohydrates.
Carbohydrates are organic molecules found in many foods, and they serve as the primary energy source for our cells. When we consume carbohydrates, our bodies break them down into glucose, which is then used by cells as fuel for various functions, including growth, repair, and maintenance.
While proteins and lipids can also provide energy, carbohydrates are typically the quickest and most efficient source. Water, on the other hand, does not provide energy itself but is essential for many metabolic processes.