**Explanation:**

A balanced diet is one that includes all the necessary nutrients in the right proportions to support proper growth and development. These nutrients include carbohydrates, proteins, fats, vitamins, minerals, and fibers. Arun's breakfast lacks carbohydrates and proteins, which are essential for providing energy and building and repairing body tissues.

**Carbohydrates:**
Carbohydrates are the main source of energy for the body. They are found in foods like bread, rice, cereals, and fruits. Arun's breakfast does not include any source of carbohydrates, as none of the items listed (orange, juice, cheese, jam) are significant sources of carbohydrates.

**Proteins:**
Proteins are essential for the growth and repair of body tissues. They are found in foods like meat, fish, eggs, dairy products, and legumes. Arun's breakfast includes cheese, which is a source of protein. However, it is not sufficient to meet the daily protein requirements of the body. Therefore, the breakfast lacks adequate protein content.

**Other Nutrients:**
While Arun's breakfast includes orange, juice, cheese, and jam, these items do not provide a sufficient amount of vitamins, minerals, and fibers.

- **Vitamins and Minerals:** Fruits and vegetables are important sources of vitamins and minerals. Although Arun's breakfast includes an orange, which is a source of vitamin C, it does not provide a variety of vitamins and minerals that are necessary for overall health.

- **Fibers:** Fibers are essential for proper digestion and bowel movements. They are found in foods like whole grains, fruits, and vegetables. Arun's breakfast does not include any significant source of fiber.

Therefore, based on the given options (a) Carbohydrates and proteins, it can be concluded that Arun's breakfast does not constitute a balanced diet because it lacks carbohydrates and proteins. To make his breakfast more balanced, Arun should consider adding sources of carbohydrates like bread or cereal and sources of protein like eggs or yogurt. Additionally, including fruits and vegetables would ensure the intake of vitamins, minerals, and fibers.

A