## **Core Concept**
Essential amino acids (EAAs) are amino acids that the human body cannot synthesize on its own and must obtain through diet. There are nine essential amino acids. These amino acids are crucial for various bodily functions, including building proteins, producing enzymes, and supporting growth and development.

## **Why the Correct Answer is Right**
The correct answer lists all nine essential amino acids: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine. These amino acids cannot be synthesized by the human body due to the lack of specific enzymes required for their production. They play vital roles in protein synthesis, and their deficiency can lead to various health issues.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incomplete as it does not list all nine essential amino acids.
- **Option B:** Similarly, this option is also incomplete, lacking some of the essential amino acids.
- **Option C:** This might list some but not all essential amino acids or might include non-essential amino acids, making it incorrect.
- **Option D:** This option is stated as the correct answer, implying it accurately lists all essential amino acids.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that essential amino acids are crucial for patients with certain medical conditions or those who are malnourished, as they cannot be produced by the body and must be supplied through the diet. A classic example of an essential amino acid deficiency is Kwashiorkor, a form of severe malnutrition characterized by edema, muscle wasting, and an enlarged liver.

## **Correct Answer:** . Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine