Answer:
They compromise most of the structural materials in the body.
Step-by-step explanation:
In order to answer the question, we need to analyze each of the answer choices separately.
⇒They are stored in the adipose tissue to provide energy for physical activities.
The statement above refers to fat in particular and lipids in general. ( Lipid is a general term and includes both oil and fats whereas fat refers to lipids which are solid at room temperature. Oil are lipids which are liquid at room temperature.) Fats are one of the key macronutrients in human diet others being proteins and carbohydrates.
Fats are used to store energy in human body. The tissue in which energy in the form of fat is stored is called adipose tissue or body fat.
⇒They comprise most of the structural materials in the body.
The statement above refers to proteins and is the correct answer. They are the most abundant organic compounds in cells and are used for building most of the structures. They are polymers of amino acids.
⇒They are micronutrients that maintain the pH of the body fluids.
The first point in the statement which makes it clear that it does not refer to proteins is the word "micronutrients". Protein is a macronutrient. Macronutrients are required in larger amounts as compared to micronutrients for physiological functioning of human body.
Micronutrients include vitamins and minerals.
⇒They are essential for the body to metabolize and absorb vitamins A, D, E, and K.
Vitamins A,D,E and K are fat-soluble and require fat for their proper absorption. Hence, the statement refers to fat.