Among the following common dairy foods, which option is a rich source of dietary protein for the human body?

Introduction / Context:
Nutrition questions often test basic awareness of which foods supply carbohydrates, fats, proteins, vitamins, and minerals. Dairy products are an important part of many diets worldwide and are known for their protein and calcium content. Identifying which items are good protein sources helps learners make healthier food choices and answer exam questions about balanced diets.

Given Data / Assumptions:

• The dairy foods listed are yogurt, milk, and cheese.
• We must decide which option is a rich source of protein.
• We assume standard cow milk based products as commonly consumed.
• The focus is on protein contribution, not on fat or sugar content.

Concept / Approach:
Proteins are macronutrients needed for growth, repair, and maintenance of body tissues. Dairy products contain high quality protein, meaning they supply all essential amino acids. Milk provides protein in liquid form, yogurt is fermented milk with similar protein content per volume, and cheese is concentrated milk protein and fat, often containing even more protein per gram than milk. Therefore, all three items listed can be considered rich sources of protein compared to many plant foods.

Step-by-Step Solution:
Step 1: Recall that one glass of milk supplies significant protein along with calcium.Step 2: Yogurt is made from milk by bacterial fermentation, which does not remove the protein, so it remains a good protein source.Step 3: Cheese is made by coagulating milk proteins, mainly casein, so it is very rich in protein per unit weight.Step 4: Each of the three dairy items individually can be called a rich source of protein.Step 5: Therefore, the combined option stating all of the above dairy foods is the correct answer.

Verification / Alternative check:
Nutritional tables show that 100 millilitres of milk and equivalent servings of yogurt and cheese all provide notable amounts of protein, often around 3 to 4 grams per 100 millilitres for milk and higher values for many cheeses. Nutrition guidelines for athletes and growing children commonly list milk, yogurt, and cheese as recommended protein sources. This independent information supports the conclusion that all the listed foods are protein rich.

Why Other Options Are Wrong:
Options A, B, and C each name a single dairy product that does provide protein, but the question is asking which option correctly identifies the rich source among the list. Since all three foods qualify, choosing only one would be incomplete. Option E, claiming that none of these foods provide protein, directly contradicts well established nutritional information, so it is clearly incorrect. Only option D recognises that all listed dairy foods are rich sources of dietary protein.

Common Pitfalls:
Some learners focus mainly on the calcium and fat content of dairy products and forget about their protein content. Others may think of cheese only as a fatty food and not as a concentrated protein source. It is useful to remember that animal milk products generally provide high quality protein, and questions with multiple dairy examples often expect the answer all of the above.

Final Answer:
All three listed foods are good protein sources, so the correct answer is All of the above dairy foods.