Final answer:
The macronutrient most essential for survival is water. It serves crucial roles in bodily functions and does not provide energy like other macronutrients such as carbohydrates, proteins, and lipids.
Step-by-step explanation:
Macronutrients are nutrients that the body needs in relatively large amounts, including carbohydrates, proteins, lipids, and water. While carbohydrates, lipids, and proteins are used by the body for energy, water does not provide energy but is essential for various physiological processes. Among the options provided: water (a), carbohydrates (b), electrolytes (c), and sugar (d), the macronutrient most essential for your survival is water because it is involved in virtually every function in the body, including but not limited to circulation, digestion, and temperature regulation.