Which of the following is NOT an essential nutrient for the body?

The choice indicating that leather is not an essential nutrient for the body is correct because leather is not a nutrient at all; it is a material derived from animal hide. The body requires essential nutrients to function properly, and these include carbohydrates, proteins, fats, vitamins, and minerals. Each of these nutrients plays a specific role in maintaining health and supporting bodily functions.

Carbohydrates provide energy, proteins are necessary for growth and repair of tissues, and vitamins are crucial for various biochemical processes and overall health. Leather, while it can be used for clothing, accessories, and other applications, does not contribute any nutritional value or health benefits to the human body. Thus, it is rightly identified as not being an essential nutrient.