How many essential amino acids are there?

The correct answer is that there are nine essential amino acids. These amino acids are termed "essential" because the body cannot synthesize them on its own; they must be obtained through diet. Essential amino acids are critical for numerous physiological functions, including protein synthesis, tissue repair, and nutrient absorption.

The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. It's important to consume them in sufficient quantities through protein-rich foods such as meat, dairy, eggs, and legumes, as they play a crucial role in muscle repair and overall health.

Other options incorrectly state a different number of essential amino acids. Twelve, fifteen, and eight do not accurately reflect the established consensus on the number of essential amino acids required by humans.