Which of the following is NOT a symptom of anemia?

Weight gain is not a symptom of anemia. Anemia typically results from a deficiency in red blood cells or hemoglobin, leading to insufficient oxygen delivery to tissues. Common symptoms associated with anemia include fatigue, pallor (paleness of the skin due to reduced blood flow), and weakness, all of which result from the body's response to decreased oxygen levels.

By contrast, weight gain is generally not linked to anemia. In fact, individuals with anemia may experience weight loss as a result of reduced appetite or illness related to underlying causes of anemia. Thus, weight gain is distinctly outside the typical symptomatology of anemia, making it the correct response in this context.