Carbohydrates are a major class of macronutrients in food. They exist as simple sugars (monosaccharides), double sugars (disaccharides), and complex carbohydrates (polysaccharides). Milk has a unique primary carbohydrate.
Step 1: Understanding the Question:
The question asks to identify the principal carbohydrate, or sugar, present in cow's milk.
Step 2: Detailed Explanation:
Let's define the sugars listed in the options:
(A) Glucose: A monosaccharide, or simple sugar. It is a fundamental energy source in living organisms but is not the main carbohydrate in milk in its free form.
(B) Fructose: A monosaccharide commonly known as "fruit sugar" due to its high concentration in fruits.
(C) Lactose: A disaccharide composed of one molecule of glucose and one molecule of galactose bonded together. It is uniquely synthesized in the mammary glands of mammals and is commonly referred to as "milk sugar". It is the main carbohydrate in milk, typically comprising around 4.5-5.0% of cow's milk by weight.
(D) Sucrose: A disaccharide composed of glucose and fructose. It is commonly known as table sugar and is extracted from sugarcane or sugar beets.
Based on these definitions, lactose is the specific and primary carbohydrate of milk.
Step 3: Final Answer:
The main carbohydrate found in cow's milk is Lactose.