Introduction:
To stay healthy, it is essential to consume a balanced diet that provides all the necessary nutrients. A balanced diet consists of a variety of foods from different food groups, ensuring that our body receives all the nutrients it needs to function properly. While carbohydrates and proteins are important components of a balanced diet, they alone cannot provide all the necessary nutrients. Therefore, the correct answer is option 'B' - a balanced diet.

Explanation:
A balanced diet includes foods from all the essential food groups in the right proportions. Each food group provides different nutrients that are vital for our health. Let's explore each food group and the nutrients they offer:

1. Fruits and Vegetables:
Fruits and vegetables are rich in vitamins, minerals, and dietary fiber. They provide essential nutrients like vitamin C, vitamin A, potassium, and folate. These nutrients strengthen our immune system, support growth and development, and help prevent chronic diseases.

2. Grains:
Grains, such as rice, wheat, oats, and bread, are a significant source of carbohydrates and provide energy to our body. They also contain dietary fiber, B vitamins, and minerals like iron and magnesium. Whole grains are particularly beneficial as they have higher fiber content and are more nutritious.

3. Protein:
Protein is essential for growth, repair, and maintenance of body tissues. It is found in foods like meat, poultry, fish, eggs, legumes, and dairy products. Proteins provide amino acids that our body uses to build and repair muscles, organs, and other structures.

4. Dairy:
Dairy products like milk, cheese, and yogurt are rich in calcium, which is important for strong bones and teeth. They also provide protein, vitamins, and minerals. Choosing low-fat or skim options is advisable to reduce the intake of saturated fats.

5. Fats and Oils:
While fats and oils should be consumed in moderation, they are still an important part of our diet. They provide essential fatty acids and fat-soluble vitamins. However, it is important to choose healthy fats, such as those found in nuts, seeds, avocados, and olive oil, and limit the intake of saturated and trans fats.

6. Sugars and Sweets:
Sugars and sweets should be consumed sparingly as they provide empty calories with little nutritional value. Excessive sugar intake can lead to various health issues, including obesity and tooth decay.

Conclusion:
A balanced diet that includes foods from all the essential food groups is necessary to stay healthy. While carbohydrates and proteins are important components of our diet, they alone cannot provide all the necessary nutrients. By consuming a variety of foods in the right proportions, we can ensure that our body receives all the essential nutrients it needs for optimal health and well-being.