Human sweat is primarily composed of water, but it also contains various dissolved solutes. The most significant solute is sodium chloride, commonly known as salt. Other components include trace amounts of urea, proteins, and minerals, but salt is the defining electrolyte that gives sweat its characteristic saline taste.

Fats (lipids) are highly reduced molecules compared to proteins and carbohydrates like glucose. Upon oxidation, fats yield approximately 9 kcal/g of energy, which is more than double the energy density of proteins or carbohydrates (approximately 4 kcal/g), making them the most efficient energy storage form.

Vitamin C is chemically known as L-ascorbic acid. It is a water-soluble vitamin that acts as a potent antioxidant in the human body, protecting cells from oxidative stress and playing a critical role in collagen synthesis and immune system support.

This question is factually problematic as sunflower oil is actually very rich in essential fatty acids like linoleic acid. Coconut oil is primarily composed of saturated fats and contains very low levels of essential polyunsaturated fatty acids. We retain the source answer 'A' due to the instruction to preserve the key, but note the potential conflict.

Vitamin K is a fat-soluble vitamin that acts as a crucial cofactor for the enzyme gamma-glutamyl carboxylase. This enzyme is responsible for the carboxylation of specific glutamic acid residues in clotting factors II, VII, IX, and X, which is essential for their activation and the subsequent blood coagulation cascade.

Vitamin A is a group of fat-soluble retinoids, including retinol, retinal, and retinoic acid. Retinol is the most common form found in the body and is chemically referred to as axerophthol. It plays a vital role in vision, immune function, and skin health.

Essential fatty acids, such as linoleic and alpha-linolenic acid, are polyunsaturated fats that the human body cannot synthesize. While most vegetable oils are rich in these, the provided answer key suggests Sunflower oil. Note: This answer is scientifically contentious as sunflower oil is typically high in linoleic acid. We preserve the provided answer key but flag it for potential conflict with standard nutritional chemistry data.

Manual review recommended: automated enrichment was incomplete for this item. The original answer and options were preserved. No Gemini key is configured. Add GEMINI_API_KEY to the local server environment or save a Gemini provider key in Settings.

Manual review recommended: automated enrichment was incomplete for this item. The original answer and options were preserved. No Gemini key is configured. Add GEMINI_API_KEY to the local server environment or save a Gemini provider key in Settings.

Lactose is a disaccharide composed of one molecule of glucose and one molecule of galactose. It is naturally found in the milk of mammals, which is why it is commonly known as milk sugar. It provides a significant source of energy for infants and is broken down in the digestive system by the enzyme lactase into its constituent monosaccharides for absorption.