A leukemia patient is at high risk of infection primarily because:

Correct answer: A. Leukemia impairs functional white blood cells

• A. Correct – leukemic proliferation crowds out and produces dysfunctional/immature WBCs, so immune defense fails despite high counts.
• B. Incorrect – a contributing local factor at most, not the primary reason.
• C. Incorrect – not the underlying mechanism in leukemia.
• D. Incorrect. Although leukemia can cause anemia, the principal reason for infection susceptibility is dysfunctional/immature leukocytes that fail to mount an effective immune response.