**Core Concept**
Iron is an essential mineral that plays a crucial role in oxygen transport, DNA synthesis, and enzyme function. Adequate dietary intake of iron from various food sources is necessary to prevent iron deficiency anemia.

**Why the Correct Answer is Right**
Iron from plant-based sources like legumes, nuts, and seeds is not as bioavailable as iron from animal sources. This is because plant-based iron is primarily in the non-heme form, which requires vitamin C to enhance absorption. On the other hand, animal-based iron is in the heme form, which is more easily absorbed by the body. Therefore, it is essential to consume vitamin C-rich foods along with plant-based iron sources to enhance absorption.

**Why Each Wrong Option is Incorrect**
**Option A:** Legumes, such as lentils and chickpeas, are actually good dietary sources of iron.
**Option C:** Nuts, like almonds and cashews, are also rich in iron and can contribute to adequate intake.

**Clinical Pearl / High-Yield Fact**
To enhance iron absorption from plant-based sources, consume vitamin C-rich foods like citrus fruits, bell peppers, or tomatoes along with iron-rich foods.

**Correct Answer:** D.