Answer:
Vaccines stimulate the body's own immune system to protect the person against subsequent infection or disease." ... The immune system develops antibodies to the disease so that it cannot make you sick again. Immunization describes the actual changes your body goes through after receiving a vaccine.
The correct answer is a dichotomous key. Basically, you use the key to decide what species an organism is by looking at what traits it has, and if it doesn't have some traits you can instantly rule out a large number of species which brings you closer to your answer of what the species is that you're looking at.
You would try to study the nucleus and the organelles of the organism to classify it
