This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood Physiology, Subject name: Physiology
Physiological leukocytosis is seen in 
Select and explain. 
A. Infancy, B. Paurition, C. Post prandial, D. ALL of the above
D: ALL of the above
Answer: D: ALL of the above 
Explanation: Physiological leukocytosis (i.e.,increase in the number of circulating leucocytes in the absence of infection or tissue injury) has no clinical significance. It is seen in the following conditions: 1. Normal infants: The count may be as high as 18-20,000/mm3 but it returns to normal level within 1-2 years. 2. Food intake and digestion ("digestive leukocytosis"):There is a mild increase which returns to normal within an hour or so. 3. Physical exercise. 4. Mental stress. 5. Pregnancy: The count may be quite high, especially during the first pregnancy. 6. Paurition: The high TLC is possibly due to tissue injury, pain, physical stress and hemorrhage. 7. Extremes of temperatures: Exposure to sun or to very low temperature can increase the WBC count.