Answer :
D. If you give someone a vaccine while they are sick the body might not be able to handle both "infections"
The Correct answer is option D
When a person is sick then it means that its immune system is already weak and the white blood cells of sick people do not work efficiently.
In this case if the body is administered with vaccination then there are chances that the person might die or become adversely sick.
Vaccination is given to evoke immune response by the help of White blood cells and if it is already not working efficiently then the vaccine can make the make person more ill.