Which of the following is a common symptom associated with anemia?

Fatigue and weakness are key symptoms commonly associated with anemia due to the decreased oxygen-carrying capacity of the blood. Anemia occurs when there is a deficiency in red blood cells or hemoglobin, which impairs the body's ability to transport oxygen to tissues and organs efficiently. As a result, individuals with anemia often experience a lack of energy and may feel unusually fatigued or weak, particularly during physical activities. This symptom directly correlates with the reduced availability of oxygen that muscles and other body systems need to function optimally.

Increased energy levels, weight gain, and hyperactivity do not typically align with the primary effects of anemia. Instead, they suggest a well-functioning body with adequate oxygenation and energy reserves, which contrasts with the experience of those suffering from anemia.