(A) hormone regulater Carbohydrate, protein and fat metabolism in our body. It is secreted by (B) gland and (C) in our diet impacts the functioning of this gland. (A), (B), (C) respectively are :

The correct answer is Thyroxine, Thyroid, Iodine.

Let's analyze the statements and complete the blanks step-by-step:

1. Hormone (A): Thyroxine is the hormone responsible for regulating the metabolism of carbohydrates, proteins, and fats in the human body to provide the best balance for growth.

2. Gland (B): Thyroxine is secreted by the thyroid gland, which is located in the neck region.

3. Dietary Component (C): Iodine is essential for the synthesis of thyroxine hormone by the thyroid gland. A deficiency of iodine in our diet can lead to thyroid malfunctioning and conditions such as goitre.

Therefore, (A), (B), and (C) respectively are Thyroxine, Thyroid, and Iodine.