**Core Concept**
The World Health Organization (WHO) defines anemia based on hemoglobin levels in different populations, considering factors like age, sex, and pregnancy status. In non-pregnant females, the WHO cut-off for anemia diagnosis is crucial for identifying individuals at risk of iron deficiency and related health problems.

**Why the Correct Answer is Right**
The WHO defines anemia in non-pregnant females as a hemoglobin level below 12 grams per deciliter (g/dL). This cut-off is based on extensive research and takes into account the average hemoglobin concentration in healthy non-pregnant women. The WHO also considers the fact that hemoglobin levels can vary across different populations and age groups, making this cut-off a reliable indicator of anemia.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the WHO cut-off for anemia in non-pregnant females is not 10 g/dL. This value is actually the cut-off for severe anemia.
* **Option B:** This option is incorrect because the WHO cut-off for anemia in non-pregnant females is not 13 g/dL. This value is actually the cut-off for anemia in pregnant women.
* **Option D:** This option is incorrect because the WHO cut-off for anemia in non-pregnant females is not 11.5 g/dL. While this value is close, it is not the exact cut-off defined by the WHO.

**Clinical Pearl / High-Yield Fact**
When diagnosing anemia in non-pregnant females, it's essential to consider the WHO cut-off of 12 g/dL to identify individuals at risk of iron deficiency and related health problems.

**Correct Answer:** C. 12 g/dL