Answer: Option 'D' is correct.
Step-by-step explanation:
When a person suffers from fever, the increased temperature of body helps the white blood cells to fight with germs. White blood cells is known as the soldiers of human body.
Fevers makes them to respond faster and kills germs at a faster rate.
And at the same time, germs can't reproduce due to higher temperature of body.
Hence, option 'D' is correct.