**Core Concept**
Iron is an essential nutrient for the human body, playing a critical role in oxygen transport, DNA synthesis, and energy production. The primary sources of dietary iron are heme iron from animal products and non-heme iron from plant-based foods.

**Why the Correct Answer is Right**
Heme iron is more easily absorbed by the body compared to non-heme iron. This is because heme iron is already in a form that can be directly used by the body, whereas non-heme iron needs to be converted into a usable form through a series of biochemical reactions. The absorption of heme iron is also influenced by several factors, including the presence of vitamin C, which can enhance absorption, and phytates, which can inhibit absorption.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not specify a particular nutrient rich in iron. While some nutrients may be rich in iron, this option is too vague to be a correct answer.
**Option B:** This option is incorrect as it does not provide a specific example of a nutrient rich in iron. Without more information, it is impossible to determine if this option is correct or not.
**Option C:** This option is incorrect as it does not mention a specific food or nutrient that is rich in iron. While some foods may be high in iron, this option is too general to be a correct answer.

**Clinical Pearl / High-Yield Fact**
When considering iron-rich foods, it's essential to note that heme iron from animal sources is more easily absorbed by the body than non-heme iron from plant-based sources. This is why individuals with strict vegetarian or vegan diets may require additional iron supplements to prevent iron deficiency anemia.

**Correct Answer: C. Red meat.