The haematopoetic injury occurs at a dose of:: (A) 2-7 Gy, (B) 7-15 Gy, (C) 40-50 Gy, (D) > 50 Gy
Answer is A. Acute radiation syndrome:

2–7 Gy – Haematopoietic injury
7–15 Gy – Injury
> 50 Gy – CVS / CNS